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 A107246 Sum of squares of octanacci numbers (Fibonacci 8-step numbers). 2

%I

%S 0,0,0,0,0,0,0,1,2,6,22,86,342,1366,5462,21846,86871,345952,1378208,

%T 5490992,21877296,87163696,347276080,1383600944,5512434480,

%U 21962292529,87500852554,348615720590,1388934122190,5533708922574,22047074027470

%N Sum of squares of octanacci numbers (Fibonacci 8-step numbers).

%C 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 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Fibonaccin-StepNumber.html">Fibonacci n-Step Number</a>.

%F a(n) = F_8(0)^2 + F_8(1)^2 + ... F_8(n)^2, where F_8(n) = A079262(n).

%Y Cf. A079262, A107239-A107245, A107247-A107248.

%K easy,nonn

%O 0,9

%A _Jonathan Vos Post_, May 27 2005

%E Corrected from a(16) on by _R. J. Mathar_, Aug 11 2009

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