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A105076 Numbers k such that 60*k^2 + 60*k + 1 is a square. 0

%I

%S 0,1,2,11,19,90,153,712,1208,5609,9514,44163,74907,347698,589745,

%T 2737424,4643056,21551697,36554706,169676155,287794595,1335857546,

%U 2265802057,10517184216,17838621864,82801616185,140443172858,651895745267

%N Numbers k such that 60*k^2 + 60*k + 1 is a square.

%F From _R. J. Mathar_, Nov 13 2009: (Start)

%F a(n) = a(n-1) + 8*a(n-2) - 8*a(n-3) - a(n-4) + a(n-5).

%F G.f.: x^2*(1+x+x^2)/((1-x)*(x^4-8*x^2+1)). (End)

%Y Cf. A103200, A001090.

%K nonn

%O 1,3

%A _Pierre CAMI_, Apr 06 2005

%E Partially edited by _Jon E. Schoenfield_, Oct 13 2019

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Last modified April 20 00:58 EDT 2021. Contains 343117 sequences. (Running on oeis4.)