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%I #14 May 13 2023 23:50:02
%S 7,43,57,93,107,143,157,193,207,243,257,293,307,343,357,393,407,443,
%T 457,493,507,543,557,593,607,643,657,693,707,743,757,793,807,843,857,
%U 893,907,943,957,993,1007,1043,1057,1093,1107,1143,1157,1193,1207,1243,1257
%N Numbers whose square ends with 49.
%C First 7 terms = 7th row in A111445.
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (1,1,-1).
%F a(1)=7, a(2)=43, a(n) = 50 + a(n-2).
%F From _Colin Barker_, Jul 04 2014: (Start)
%F a(n) = (11*(-1)^n + 50*n - 25)/2.
%F a(n) = a(n-1) + a(n-2) - a(n-3).
%F G.f.: x*(7*x^2+36*x+7) / ((x-1)^2*(x+1)). (End)
%o (PARI) select(n->n^2%100==49, vector(10^3,n,n)) \\ _Colin Barker_, Jul 04 2014
%Y A111445 Triangle read by rows: row n contains the first n numbers whose squares end in n^2.
%K base,nonn,easy
%O 1,1
%A _Zak Seidov_, Apr 07 2009
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