This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A195146 #36 Jan 16 2023 08:53:35
%S A195146 0,1,16,33,64,97,144,193,256,321,400,481,576,673,784,897,1024,1153,
%T A195146 1296,1441,1600,1761,1936,2113,2304,2497,2704,2913,3136,3361,3600,
%U A195146 3841,4096,4353,4624,4897,5184,5473,5776,6081,6400,6721,7056,7393,7744,8097,8464
%N A195146 Concentric 16-gonal numbers.
%C A195146 Concentric hexadecagonal numbers or concentric hexakaidecagonal numbers.
%C A195146 Sequence found by reading the line from 0, in the direction 0, 16, ..., and the same line from 1, in the direction 1, 33, ..., in the square spiral whose vertices are the generalized decagonal numbers A074377. Main axis, perpendicular to A033996 in the same spiral.
%H A195146 Vincenzo Librandi, <a href="/A195146/b195146.txt">Table of n, a(n) for n = 0..10000</a>
%H A195146 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (2,0,-2,1).
%F A195146 From _Vincenzo Librandi_, Sep 27 2011: (Start)
%F A195146 a(n) = (8*n^2 + 3*(-1)^n - 3)/2;
%F A195146 a(n) = -a(n-1) + 8*n^2 - 8*n + 1. (End)
%F A195146 G.f. -x*(1+14*x+x^2) / ( (1+x)*(x-1)^3 ). - _R. J. Mathar_, Sep 18 2011
%F A195146 Sum_{n>=1} 1/a(n) = Pi^2/96 + tan(sqrt(3)*Pi/4)*Pi/(8*sqrt(3)). - _Amiram Eldar_, Jan 16 2023
%t A195146 LinearRecurrence[{2, 0, -2, 1}, {0, 1, 16, 33}, 50] (* _Amiram Eldar_, Jan 16 2023 *)
%o A195146 (Magma) [(8*n^2+3*(-1)^n-3)/2: n in [0..50]]; // _Vincenzo Librandi_, Sep 27 2011
%o A195146 (PARI) a(n)=(8*n^2+3*(-1)^n-3)/2 \\ _Charles R Greathouse IV_, Oct 07 2015
%Y A195146 A016802 and A195315 interleaved.
%Y A195146 Cf. A032528, A033996, A074377, A077221, A195142, A195143, A195145, A195147, A195148, A195149.
%Y A195146 Column 16 of A195040.
%K A195146 nonn,easy
%O A195146 0,3
%A A195146 _Omar E. Pol_, Sep 17 2011