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URL: https://oeis.org/A037611

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A037611
Base-4 digits are, in order, the first n terms of the periodic sequence with initial period 1,3,2.
1
1, 7, 30, 121, 487, 1950, 7801, 31207, 124830, 499321, 1997287, 7989150, 31956601, 127826407, 511305630, 2045222521, 8180890087, 32723560350, 130894241401, 523576965607, 2094307862430, 8377231449721, 33508925798887, 134035703195550, 536142812782201, 2144571251128807
OFFSET
1,2
FORMULA
From R. J. Mathar, Apr 27 2015: (Start)
G.f.: x*(1+x)*(2*x+1) / ( (x-1)*(4*x-1)*(1+x+x^2) ).
A007090(a(n)) = A037617(n). (End)
a(n) ~ (10/21)*4^n = (10/21)*A000302(n). - Stefano Spezia, Oct 15 2023
MATHEMATICA
LinearRecurrence[{4, 0, 1, -4}, {1, 7, 30, 121}, 30] (* Paolo Xausa, Oct 16 2023 *)
PROG
(PARI) a(n)=([0, 1, 0, 0; 0, 0, 1, 0; 0, 0, 0, 1; -4, 1, 0, 4]^(n-1)*[1; 7; 30; 121])[1, 1] \\ Charles R Greathouse IV, Feb 13 2017
CROSSREFS
KEYWORD
nonn,base,easy
EXTENSIONS
a(24)-a(26) from Stefano Spezia, Oct 15 2023
STATUS
approved