A113876 a(n) = a(n-1) + 2^(k(n)), where k(n) is the n-th term of the sequence formed by k(1)=0 together with the numbers A042964.
1, 5, 13, 77, 205, 1229, 3277, 19661, 52429, 314573, 838861, 5033165, 13421773, 80530637, 214748365, 1288490189, 3435973837, 20615843021, 54975581389, 329853488333, 879609302221, 5277655813325, 14073748835533, 84442493013197, 225179981368525, 1351079888211149
Offset: 1
Links
- Vincenzo Librandi, Table of n, a(n) for n = 1..300
- Index entries for linear recurrences with constant coefficients, signature (1,16,-16).
Programs
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PARI
a(n)=(4+(-4)^n+5*4^n)/20 \\ Charles R Greathouse IV, Jul 08 2024
Formula
G.f.: (1+x-8*x^2)/(2*(-1+x)*(-1+4*x)*(1+4*x)). - Vaclav Kotesovec, Nov 28 2012
a(n) = (4 + (-4)^n + 5*4^n)/20. - Gerry Martens, May 26 2024
Extensions
Edited with better definition and offset corrected by Omar E. Pol, Jan 08 2009