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A130251
Partial sums of A130249.
11
0, 2, 4, 7, 10, 14, 18, 22, 26, 30, 34, 39, 44, 49, 54, 59, 64, 69, 74, 79, 84, 90, 96, 102, 108, 114, 120, 126, 132, 138, 144, 150, 156, 162, 168, 174, 180, 186, 192, 198, 204, 210, 216, 223, 230, 237, 244, 251, 258, 265, 272, 279, 286, 293, 300, 307, 314, 321
OFFSET
0,2
LINKS
FORMULA
a(n) = Sum_{k=0..n} A130249(k).
a(n) = (n+1)*floor(log_2(3n+1)) - 1/2*A001045(floor(log_2(3n+1))+2)-1).
G.f.: 1/(1-x)^2*Sum{k>=1, x^A001045(k)}.
EXAMPLE
G.f. = 2*x + 4*x^2 + 7*x^3 + 10*x^4 + 14*x^5 + 18*x^6 + 22*x^7 + ... - Michael Somos, Sep 17 2018
MATHEMATICA
Join[{0}, Table[Sum[Floor[Log[2, 3*k + 1]], {k, 1, n}], {n, 1, 2500}]] (* G. C. Greubel, Sep 09 2018 *)
PROG
(PARI) for(n=0, 100, print1(sum(k=1, n, floor(log(3*k+1)/log(2))), ", ")) \\ G. C. Greubel, Sep 09 2018
(Magma) [0] cat [(&+[Floor(Log(3*k+1)/Log(2)) : k in [1..n]]): n in [1..100]]; // G. C. Greubel, Sep 09 2018
KEYWORD
nonn
AUTHOR
Hieronymus Fischer, May 20 2007
STATUS
approved