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 A107246 #14 Feb 16 2025 08:32:57
%S A107246 0,0,0,0,0,0,0,1,2,6,22,86,342,1366,5462,21846,86871,345952,1378208,
%T A107246 5490992,21877296,87163696,347276080,1383600944,5512434480,
%U A107246 21962292529,87500852554,348615720590,1388934122190,5533708922574,22047074027470
%N A107246 Sum of squares of octanacci numbers (Fibonacci 8-step numbers).
%C A107246 Primes in this sequence include: a(8) = 2, a(17) = 280927. Semiprimes in this sequence include: a(9) = 6 = 2 * 3, a(10) = 22 = 2 * 11, a(11) = 86 = 2 * 43, a(13) = 1366 = 2 * 683, a(14) = 5462 = 2 * 2731, a(24) = 5512110374 = 2 * 2756055187, a(25) = 21961968423 = 3 * 7320656141, a(36) = 88177707994468342 = 2 * 44088853997234171.
%H A107246 Harvey P. Dale, <a href="/A107246/b107246.txt">Table of n, a(n) for n = 0..1000</a>
%H A107246 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Fibonaccin-StepNumber.html">Fibonacci n-Step Number</a>.
%H A107246 <a href="/index/Rec#order_37">Index entries for linear recurrences with constant coefficients</a>, signature (3, 2, 4, 8, 14, 30, 60, 120, -266, -24, -38, -32, 120, -22, -50, -64, 136, 16, 30, 22, -68, 0, 10, 18, -28, 0, -6, -8, 14, 0, 0, -2, 2, 0, 0, 1, -1).
%F A107246 a(n) = F_8(0)^2 + F_8(1)^2 + ... F_8(n)^2, where F_8(n) = A079262(n).
%t A107246 Accumulate[LinearRecurrence[{1,1,1,1,1,1,1,1},{0,0,0,0,0,0,0,1},40]^2] (* _Harvey P. Dale_, May 25 2014 *)
%t A107246 LinearRecurrence[{3, 2, 4, 8, 14, 30, 60, 120, -266, -24, -38, -32, 120, -22, -50, -64, 136, 16, 30, 22, -68, 0, 10, 18, -28, 0, -6, -8, 14, 0, 0, -2, 2, 0, 0, 1, -1},{0, 0, 0, 0, 0, 0, 0, 1, 2, 6, 22, 86, 342, 1366, 5462, 21846, 86871, 345952, 1378208, 5490992, 21877296, 87163696, 347276080, 1383600944, 5512434480, 21962292529, 87500852554, 348615720590, 1388934122190, 5533708922574, 22047074027470, 87838639467470, 349961474550734, 1394295671696334, 5555069815204303, 22132178477202944, 88177707994792448},31] (* _Ray Chandler_, Aug 02 2015 *)
%Y A107246 Cf. A079262, A107239-A107245, A107247-A107248.
%K A107246 easy,nonn
%O A107246 0,9
%A A107246 _Jonathan Vos Post_, May 27 2005
%E A107246 Corrected from a(16) on by _R. J. Mathar_, Aug 11 2009