A027177 - OEIS

A027177

a(n) = A027170(n, floor(n/2)).

1, 3, 10, 19, 42, 76, 156, 283, 570, 1046, 2096, 3890, 7784, 14582, 29168, 55051, 110106, 209062, 418128, 797806, 1595616, 3056868, 6113740, 11752674, 23505352, 45316896, 90633796, 175175816, 350351636, 678639146, 1357278296

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..30.

FORMULA

D-finite with recurrence 2*(n+3)*a(n) -4*a(n-1) +(-7*n-9)*a(n-2) -2*a(n-3) +4*(-n+3)*a(n-4) +12*(-3*n+1)=0. - R. J. Mathar, May 06 2026

D-finite with recurrence -(n+3)*(3*n-1)*a(n) +(-3*n^2+6*n+10)*a(n-1) +2*(n+2)*(6*n-5)*a(n-2) +12*n*(n-2)*a(n-3) +4*(18*n^2-12*n-7)=0. - R. J. Mathar, May 06 2026

a(n) = 2*A001405(n+2) + A001405(n) - 4. - Christian Krause, May 14 2026

MAPLE

A027177 := proc(n)

A027170(n, floor(n/2)) ;

end proc:

seq(A027177(n), n=0..50) ; # R. J. Mathar, May 06 2026

CROSSREFS

Cf. A001405, A027170.

Sequence in context: A135446 A160002 A294421 * A048343 A056789 A174476

Adjacent sequences: A027174 A027175 A027176 * A027178 A027179 A027180

KEYWORD

nonn,easy,changed

AUTHOR

Clark Kimberling

STATUS

approved