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%I #8 May 13 2022 17:20:15
%S 287,532,17145051,32963672,1106094475927,2126616990876,
%T 71358579001465427,137196568515066592,4603627364594444737551,
%U 8851099419054387781412,296998415728087428795555787,571019827783678204813603176,19160555787678205016722039960967
%N Pentagonal numbers (A000326) that are the sum of seven consecutive pentagonal numbers.
%H Colin Barker, <a href="/A259402/b259402.txt">Table of n, a(n) for n = 1..416</a>
%H <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,64514,-64514,-1,1).
%F G.f.: -7*x*(1968*x^4+1813*x^3-195857*x^2+35*x+41) / ((x-1)*(x^2-254*x+1)*(x^2+254*x+1)).
%e 287 is in the sequence because P(14) = 287 = 5+12+22+35+51+70+92 = P(2)+ ... +P(8).
%t LinearRecurrence[{1,64514,-64514,-1,1},{287,532,17145051,32963672,1106094475927},20] (* _Harvey P. Dale_, May 13 2022 *)
%o (PARI) Vec(-7*x*(1968*x^4+1813*x^3-195857*x^2+35*x+41)/((x-1)*(x^2-254*x+1)*(x^2+254*x+1)) + O(x^20))
%Y Cf. A000326, A133301, A257714, A257715, A259403, A259404.
%K nonn,easy
%O 1,1
%A _Colin Barker_, Jun 26 2015
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