A225352 - OEIS

A225352

Number of 12Xn -1,1 arrays such that the sum over i=1..12,j=1..n of i*x(i,j) is zero, the sum of x(i,j) is zero, and rows are nondecreasing (number of ways to distribute n-across galley oarsmen left-right at 12 fore-aft positions so that there are no turning moments on the ship).

58, 2837, 47990, 437763, 2680534, 12439855, 47084448, 152452967, 436320984, 1129965973, 2694285574, 5993361143, 12566218452, 25037146431, 47716202440, 87454967053, 154837885246, 265807450011, 443841357932, 722822838305

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Row 12 of A225345

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = a(n-1) +a(n-2) -a(n-5) -a(n-7) +a(n-14) +2*a(n-15) +a(n-16) -a(n-19) -a(n-20) -a(n-21) -2*a(n-22) -a(n-23) -a(n-24) -a(n-26) +2*a(n-27) +2*a(n-28) +2*a(n-29) +2*a(n-30) +a(n-31) +a(n-32) -a(n-34) -a(n-35) -2*a(n-36) -2*a(n-37) -2*a(n-38) -2*a(n-39) +a(n-40) +a(n-42) +a(n-43) +2*a(n-44) +a(n-45) +a(n-46) +a(n-47) -a(n-50) -2*a(n-51) -a(n-52) +a(n-59) +a(n-61) -a(n-64) -a(n-65) +a(n-66)

EXAMPLE

Some solutions for n=4

.-1.-1.-1..1...-1.-1.-1.-1...-1.-1.-1..1...-1.-1.-1.-1...-1.-1.-1..1

.-1.-1.-1..1...-1.-1.-1..1...-1.-1.-1..1...-1..1..1..1...-1.-1.-1.-1

.-1.-1..1..1...-1..1..1..1....1..1..1..1...-1.-1..1..1...-1..1..1..1

.-1..1..1..1....1..1..1..1...-1..1..1..1....1..1..1..1...-1..1..1..1

..1..1..1..1...-1.-1..1..1...-1..1..1..1...-1.-1.-1..1...-1.-1..1..1

.-1..1..1..1....1..1..1..1...-1.-1.-1..1...-1.-1..1..1...-1.-1.-1..1

.-1.-1..1..1...-1.-1.-1.-1...-1.-1.-1.-1...-1.-1..1..1....1..1..1..1

.-1.-1.-1..1....1..1..1..1...-1.-1..1..1....1..1..1..1...-1..1..1..1

.-1.-1.-1.-1...-1.-1.-1..1....1..1..1..1...-1.-1.-1.-1....1..1..1..1

..1..1..1..1...-1..1..1..1...-1.-1.-1.-1...-1..1..1..1...-1..1..1..1

.-1.-1.-1..1...-1.-1.-1.-1....1..1..1..1...-1.-1.-1..1...-1.-1.-1.-1

.-1.-1..1..1...-1.-1..1..1...-1.-1.-1..1...-1.-1..1..1...-1.-1.-1.-1

CROSSREFS

Sequence in context: A017721 A280111 A281031 * A278097 A299467 A334935

Adjacent sequences: A225349 A225350 A225351 * A225353 A225354 A225355

KEYWORD

nonn

AUTHOR

R. H. Hardin, May 05 2013

STATUS

approved