A237991 a(n) = 991*n^2 + 1.

1, 992, 3965, 8920, 15857, 24776, 35677, 48560, 63425, 80272, 99101, 119912, 142705, 167480, 194237, 222976, 253697, 286400, 321085, 357752, 396401, 437032, 479645, 524240, 570817, 619376, 669917, 722440, 776945, 833432, 891901, 952352, 1014785, 1079200

Offset

0,2

Comments

a(n) is nonsquare for 1 <= n < 12055735790331359447442538767.

Links

Table of n, a(n) for n=0..33.

Index entries for linear recurrences with constant coefficients, signature (3,-3,1).

Formula

G.f.: (1 + 989*x + 992*x^2)/(1 - x)^3.

a(n) = a(n-1) + 991*(2*n - 1).

Maple

seq(991*n^2+1, n=0..33);

Mathematica

Table[991*n^2 + 1, {n, 0, 33}]

Prog

(Magma) [991*n^2+1: n in [0..33]];
(PARI) for(n=0, 33, print1(991*n^2+1, ", "));

Crossrefs

Cf. A154651.

Sequence in context: A161926 A172698 A109149 * A158683 A030645 A010463

Adjacent sequences: A237988 A237989 A237990 * A237992 A237993 A237994

Keyword

nonn,easy

Author

Arkadiusz Wesolowski, Feb 16 2014

Status

approved