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%I #28 Sep 08 2022 08:45:58
%S 4,44,124,244,404,604,844,1124,1444,1804,2204,2644,3124,3644,4204,
%T 4804,5444,6124,6844,7604,8404,9244,10124,11044,12004,13004,14044,
%U 15124,16244,17404,18604,19844,21124,22444,23804,25204,26644,28124,29644,31204,32804
%N a(n) = 4*(5*n^2 - 5*n + 1).
%C The natural numbers of the form 5*n^2-1, with n odd. See also A158491 for the cases where n is even. - _Giovanni Teofilatto_, Oct 10 2011
%H Vincenzo Librandi, <a href="/A193448/b193448.txt">Table of n, a(n) for n = 1..10000</a>
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F a(n) = 4*A062786(n).
%F G.f.: -4*x*(1+8*x+x^2) / (x-1)^3. - _R. J. Mathar_, Aug 26 2011
%F a(n) = 3*a(n-1)-3*a(n-2)+a(n-3) for n>3. - _Wesley Ivan Hurt_, Nov 21 2015
%p A193448:=n->4*(5*n^2 - 5*n + 1): seq(A193448(n), n=1..50); # _Wesley Ivan Hurt_, Nov 21 2015
%t Table[4*(5*n^2 - 5*n + 1), {n, 50}] (* _Wesley Ivan Hurt_, Nov 21 2015 *)
%o (Magma) [4*(5*n^2-5*n+1): n in [1..50]]; // _Vincenzo Librandi_, Aug 30 2011
%o (PARI) a(n) = 4*(5*n^2 - 5*n + 1) \\ _Anders Hellström_, Nov 21 2015
%Y Cf. A062786, A158491.
%K nonn,easy
%O 1,1
%A _Giovanni Teofilatto_, Jul 26 2011
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