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A326725
a(n) = (1/2)*n*(5*n - 7); row 5 of A326728.
3
0, -1, 3, 12, 26, 45, 69, 98, 132, 171, 215, 264, 318, 377, 441, 510, 584, 663, 747, 836, 930, 1029, 1133, 1242, 1356, 1475, 1599, 1728, 1862, 2001, 2145, 2294, 2448, 2607, 2771, 2940, 3114, 3293, 3477, 3666, 3860, 4059, 4263, 4472, 4686, 4905, 5129, 5358, 5592
OFFSET
0,3
FORMULA
From Colin Barker, Aug 04 2019: (Start)
G.f.: -x*(1 - 6*x) / (1 - x)^3.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>2.
(End)
MAPLE
a := n -> (1/2)*n*(5*n - 7): seq(a(n), n=0..48);
PROG
(PARI) concat(0, Vec(-x*(1 - 6*x) / (1 - x)^3 + O(x^40))) \\ Colin Barker, Aug 04 2019
CROSSREFS
Cf. A326728.
Sequence in context: A366984 A237650 A199242 * A169678 A294366 A110859
KEYWORD
sign,easy
AUTHOR
Peter Luschny, Aug 04 2019
STATUS
approved