A174994 Repeat (8*n+4)^2.
16, 16, 144, 144, 400, 400, 784, 784, 1296, 1296, 1936, 1936, 2704, 2704, 3600, 3600, 4624, 4624, 5776, 5776, 7056, 7056, 8464, 8464, 10000, 10000, 11664, 11664, 13456, 13456, 15376, 15376, 17424, 17424, 19600, 19600, 21904, 21904, 24336, 24336, 26896, 26896, 29584, 29584, 32400, 32400, 35344, 35344
Offset: 0
Links
- Colin Barker, Table of n, a(n) for n = 0..1000
- Index entries for linear recurrences with constant coefficients, signature (1,2,-2,-1,1).
Programs
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Mathematica
(8*Floor[Range[0, 50]/2] + 4)^2 (* Wesley Ivan Hurt, Jul 23 2025 *)
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PARI
Vec((-16-96*x^2-16*x^4)/((1+x)^2*(x-1)^3) + O(x^100)) \\ Colin Barker, Jan 26 2016
Formula
a(2n) = a(2n+1) = A017114(n).
From R. J. Mathar, Dec 02 2010: (Start)
a(n) = a(n-1) +2*a(n-2) -2*a(n-3) -a(n-4) +a(n-5).
G.f.: ( -16-96*x^2-16*x^4 ) / ( (1+x)^2*(x-1)^3 ). (End)
From Colin Barker, Jan 26 2016: (Start)
a(n) = 8*(2*n^2+2*(-1)^n*n+2*n+(-1)^n+1).
a(n) = 16*n^2+32*n+16 for n even.
a(n) = 16*n^2 for n odd. (End)
a(n) = (8*floor(n/2)+4)^2. - Bruno Berselli, Jan 26 2016