A014792 Squares of even heptagonal numbers.

0, 324, 1156, 12544, 21904, 81796, 116964, 291600, 379456, 763876, 940900, 1658944, 1971216, 3175524, 3678724, 5550736, 6310144, 9060100, 10150596, 14017536, 15523600, 20775364, 22791076, 29724304, 32353344, 41293476, 44649124, 55950400, 60155536, 74200996

Offset

0,2

Links

Colin Barker, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (1,4,-4,-6,6,4,-4,-1,1).

Formula

From Colin Barker, Dec 17 2015: (Start)

a(n) = (1/2)*(200*n^4 - 120*n^3 + 18*n^2) for n even.

a(n) = (1/2)*(200*n^4 + 280*n^3 + 138*n^2 + 28*n + 2) for n odd.

G.f.: 4*x*(81 + 208*x + 2523*x^2 + 1508*x^3 + 4071*x^4 + 680*x^5 + 525*x^6 + 4*x^7) / ((1-x)^5*(1+x)^4).

(End)

Mathematica

Select[Table[(n(5n-3))/2, {n, 0, 60}], EvenQ]^2 (* Harvey P. Dale, Jul 24 2015 *)

Prog

(PARI) concat(0, Vec(4*x*(81+208*x+2523*x^2+1508*x^3+4071*x^4+680*x^5+525*x^6+4*x^7) / ((1-x)^5*(1+x)^4) + O(x^40))) \\ Colin Barker, Dec 17 2015

Crossrefs

Cf. A000566, A014637, A014640, A014773.

Sequence in context: A096526 A111278 A241502 * A287634 A329613 A202094

Adjacent sequences: A014789 A014790 A014791 * A014793 A014794 A014795

Keyword

nonn,easy

Author

Mohammad K. Azarian

Extensions

More terms from Patrick De Geest, Aug 17 2000

Status

approved