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 A332243 #50 Nov 18 2023 19:35:59
%S A332243 13,133,373,733,1213,1813,2533,3373,4333,5413,6613,7933,9373,10933,
%T A332243 12613,14413,16333,18373,20533,22813,25213,27733,30373,33133,36013,
%U A332243 39013,42133,45373,48733,52213,55813,59533,63373,67333,71413,75613,79933,84373
%N A332243 Starhex honeycomb numbers: a(n) = 13 + 60*n + 60*n^2.
%D A332243 M. Gardner, Time Travel and Other Mathematical Bewilderments. Freeman, NY, 1988, p. 20.
%H A332243 John Elias, <a href="/A332243/a332243.png">Illustration of Initial Terms</a>
%H A332243 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A332243 a(n) = 12*(5*n*(n + 1) + 1) + 1.
%F A332243 From _Stefano Spezia_, Feb 07 2020: (Start)
%F A332243 O.g.f.: (13 + 94*x + 13*x^2)/(1 - x)^3.
%F A332243 E.g.f.: exp(x)*(13 + 120*x + 60*x^2).
%F A332243 a(n) = 3*a(n-1) - 3*a(n-2) + a(n-2) for n > 2. (End)
%F A332243 a(n) = A082369(A001844(n)). - _M. F. Hasler_, Jun 09 2023
%e A332243 Example: a(2) = 13 + 60*2 + 60*2^2 = 373.
%e A332243 Illustration of initial terms:
%e A332243 . 0
%e A332243 . 0 0 0 0
%e A332243 . 0 0 0
%e A332243 . 0 0 0 0 0 0
%e A332243 . 0 0 0 0 * * 0 * * 0 0 0 0
%e A332243 . 0 0 0 * * * * * * 0 0 0
%e A332243 . 0 0 0 0 * * 0 * * 0 0 0 0
%e A332243 . 0 * * 0 0 0 0 * * 0
%e A332243 . * * * 0 0 0 * * *
%e A332243 . 0 * * 0 0 0 0 * * 0
%e A332243 . 0 0 0 0 * * 0 * * 0 0 0 0
%e A332243 . 0 0 0 * * * * * * 0 0 0
%e A332243 . 0 0 0 0 0 * * 0 * * 0 0 0 0
%e A332243 . 0 * * 0 0 0 0 0 0 0
%e A332243 . * 0 * 0 0 0
%e A332243 . 0 * * 0 0 0 0 0
%e A332243 . 0 0
%e A332243 .
%e A332243 . 13 133
%t A332243 Array[12 (5 #^2 + 5 # + 1) + 1 &, 38, 0] (* _Michael De Vlieger_, Feb 07 2020 *)
%t A332243 LinearRecurrence[{3,-3,1},{13,133,373},40] (* _Harvey P. Dale_, Nov 18 2023 *)
%o A332243 (PARI) A332243(n)=n*(n+1)*60+13 \\ _M. F. Hasler_, Jun 09 2023
%Y A332243 Cf. A003154, A003215, A062786.
%Y A332243 Subsequence of A082369: cf. formula.
%K A332243 easy,nonn
%O A332243 0,1
%A A332243 _John Elias_, Feb 07 2020