A188671 A000145(n) / 8 - (n^5 + 1).

1, 0, -24, -32, 108, 275, -176, -1056, 45, 3157, 1080, -6541, -836, 16839, 2072, -33824, 1188, 67100, 1672, -95883, 19162, 161083, -8208, -224653, 2707, 371325, 67500, -520025, -1188, 870551, 8512, -1082400, 148334, 1419889, 10428, -1588228

Offset

1,3

Comments

Theorem 2 in the Hales reference defines t_p = (n_p - 8(p^5 + 1)) / (32 p^(5/2)) where n_p is the number of ways to express p as a sum of 12 squares.

Links

Table of n, a(n) for n=1..36.

T. C. Hales, The Mathematical Work of the 2010 Fields Medalists, Notices Amer. Math. Soc, 58 (No. 3, Mar 2011), 453-457. See p. 457, Theorem 2.

Formula

G.f.: ((Sum_{k} x^k^2)^12 - 1) / 8 - (2*x + 21*x^2 + 76*x^3 + 16*x^4 + 6*x^5 - x^6) / (1 - x)^6.

a(n) = A000145(n) / 8 - (n^5 + 1).

Example

x - 24*x^3 - 32*x^4 + 108*x^5 + 275*x^6 - 176*x^7 - 1056*x^8 + 45*x^9 + ...

Prog

(PARI) {a(n) = if( n<1, 0, polcoeff( sum( k = 1, sqrtint(n), 2 * x^k^2, 1 + x*O(x^n))^12, n) / 8 - (n^5 + 1))}

Crossrefs

Cf. A000145.

Sequence in context: A269424 A319928 A025102 * A166648 A231468 A366422

Adjacent sequences: A188668 A188669 A188670 * A188672 A188673 A188674

Keyword

sign

Author

Michael Somos, Apr 11 2011

Status

approved