A055419 Number of points in N^n of norm <= 4.

1, 5, 17, 54, 165, 482, 1319, 3390, 8262, 19250, 43154, 93601, 197381, 406200, 817954, 1614348, 3126068, 5943728, 11103912, 20396957, 36869790, 65637607, 115178814, 199377387, 340708159, 575150851, 959691775, 1583660542

Offset

0,2

Links

Andrew Howroyd, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (17,-136,680,-2380,6188,-12376,19448,-24310,24310,-19448,12376,-6188,2380,-680,136,-17,1).

Formula

Empirical g.f.: (11*x^16 -164*x^15 +936*x^14 -2841*x^13 +5310*x^12 -6697*x^11 +6044*x^10 -3984*x^9 +1734*x^8 -75*x^7 -741*x^6 +827*x^5 -539*x^4 +235*x^3 -68*x^2 +12*x -1) / (x -1)^17. - Colin Barker, Jul 07 2013

Prog

(PARI) a(n)=1+n*(102790985472000-87431013100800*n+75058571712384*n^2-509681688816*n^3-9890818275520*n^4+4234520293640*n^5-583274764072*n^6+15882957233*n^7+6814876640*n^8-868418980*n^9+40195792*n^10+400582*n^11-113120*n^12+5140*n^13-104*n^14+n^15)/20922789888000 \\ Charles R Greathouse IV, May 29 2026

Crossrefs

Row n=4 of A302998.

Sequence in context: A195689 A079363 A034346 * A027091 A183712 A244235

Adjacent sequences: A055416 A055417 A055418 * A055420 A055421 A055422

Keyword

nonn,easy

Author

David W. Wilson

Status

approved