A391995 a(n) = (4*n^3 - 18*n^2 - 4*n + 9*(1 - (-1)^n)) / 48.

0, 0, -1, -1, -1, 1, 4, 10, 18, 30, 45, 65, 89, 119, 154, 196, 244, 300, 363, 435, 515, 605, 704, 814, 934, 1066, 1209, 1365, 1533, 1715, 1910, 2120, 2344, 2584, 2839, 3111, 3399, 3705, 4028, 4370, 4730, 5110, 5509, 5929, 6369, 6831, 7314, 7820, 8348, 8900, 9475

Offset

0,7

Links

Table of n, a(n) for n=0..50.

Formula

gf(k) = (2*a(k)*x^2 - A212964(k)*x)/(x^3 - 3*x^2 + 3*x - 1) is the g.f. of row k of A392248.

Maple

a := n -> (4*n^3 - 18*n^2 - 4*n + 9*(1-(-1)^n))/48: seq(a(n), n = 0..50);

Mathematica

LinearRecurrence[{3, -2, -2, 3, -1}, {0, 0, -1, -1, -1}, 50] (* Hugo Pfoertner, Jan 09 2026 *)

Crossrefs

Cf. A212964, A392248.

Sequence in context: A112557 A332490 A008246 * A301284 A364685 A382069

Adjacent sequences: A391992 A391993 A391994 * A391996 A391997 A391998

Keyword

sign,easy

Author

Peter Luschny, Jan 09 2026

Status

approved