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 A257975 Heptagonal numbers (A000566) that are the sum of five consecutive heptagonal numbers. 2
 970, 3940, 219246804790, 205684244417408273530, 11480068853945505053489115880, 47065929034956905708053692550, 2626939693541678540279445026253849400, 2464437767031050248773603452558570281788774040, 137550230606703955058365608367051590003016395627772390 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Colin Barker, Table of n, a(n) for n = 1..160 Index entries for linear recurrences with constant coefficients, signature (1,0,0,11981655542024930675232002,-11981655542024930675232002,0,0,-1,1). FORMULA G.f.: -10*x*(211462*x^8 +198379896430716*x^7 +11072383489254815935515*x^6 +34322119735654912553073*x^5 -14213722750292211889419959*x^4 +20568424419816146874*x^3 +21924680085*x^2 +297*x +97) / ((x -1)*(x^2 -1860498*x +1)*(x^2 +1860498*x +1)*(x^4 +3461452808002*x^2 +1)). EXAMPLE 970 is in the sequence because H(20) = 970 = 112 + 148 + 189 + 235 + 286 = H(7)+...+H(11). PROG (PARI) Vec(-10*x*(211462*x^8 +198379896430716*x^7 +11072383489254815935515*x^6 +34322119735654912553073*x^5 -14213722750292211889419959*x^4 +20568424419816146874*x^3 +21924680085*x^2 +297*x +97) / ((x -1)*(x^2 -1860498*x +1)*(x^2 +1860498*x +1)*(x^4 +3461452808002*x^2 +1)) + O(x^20)) \\ Colin Barker, May 15 2015 CROSSREFS Cf. A000566, A133324, A257954. Sequence in context: A175991 A030251 A252196 * A217161 A243861 A171771 Adjacent sequences:  A257972 A257973 A257974 * A257976 A257977 A257978 KEYWORD nonn,easy AUTHOR Colin Barker, May 15 2015 STATUS approved

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Last modified May 15 23:13 EDT 2021. Contains 343937 sequences. (Running on oeis4.)