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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
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
1,2
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
PROG
(PARI) a(n)=(4+(-4)^n+5*4^n)/20 \\ Charles R Greathouse IV, Jul 08 2024
KEYWORD
nonn,easy
AUTHOR
Artur Jasinski, Jan 27 2006
EXTENSIONS
Edited with better definition and offset corrected by Omar E. Pol, Jan 08 2009
STATUS
approved