A157512 - OEIS

A157512

Partial sums of A157502.

2, 8, 16, 26, 38, 52, 70, 90, 112, 136, 162, 190, 220, 252, 286, 324, 364, 406, 450, 496, 544, 594, 646, 700, 756, 814, 874, 936, 1002, 1070, 1140, 1212, 1286, 1362, 1440, 1520, 1602, 1686, 1772, 1860, 1950, 2042, 2136, 2232, 2330, 2432, 2536

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..47.

FORMULA

Set R(n) = floor(A157502(n)/2) and S(n) = floor(sqrt(A157502(n))/2); then a(n) = R(n)*(R(n) + 1) - (4*S(n)^3 + 6*S(n)^2 + 2*S(n))/3.

EXAMPLE

a(4) = 2 + 6 + 8 + 10 = 26.

PROG

(PARI) lista(nn) = {s = 0; forstep (i = 2, nn, 2, if (! issquare(i), s+=i; print1(s, ", "); ); ); } \\ Michel Marcus, Aug 26 2013

CROSSREFS

Cf. A157502.

Sequence in context: A169925 A225289 A322945 * A252594 A137882 A194643

Adjacent sequences: A157509 A157510 A157511 * A157513 A157514 A157515

KEYWORD

nonn

AUTHOR

Gerald Hillier, Mar 02 2009

EXTENSIONS

More terms from Michel Marcus, Aug 26 2013

STATUS

approved