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 A014792 Squares of even heptagonal numbers. 5
 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 (list; graph; refs; listen; history; text; internal format)
 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 EXTENSIONS More terms from Patrick De Geest, Aug 17 2000 STATUS approved

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Last modified January 25 07:56 EST 2020. Contains 331241 sequences. (Running on oeis4.)