[go: up one dir, main page]

login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A335063
a(n) = Sum_{k=0..n} (binomial(n,k) mod 2) * k.
2
0, 1, 2, 6, 4, 10, 12, 28, 8, 18, 20, 44, 24, 52, 56, 120, 16, 34, 36, 76, 40, 84, 88, 184, 48, 100, 104, 216, 112, 232, 240, 496, 32, 66, 68, 140, 72, 148, 152, 312, 80, 164, 168, 344, 176, 360, 368, 752, 96, 196, 200, 408, 208, 424, 432, 880, 224, 456, 464, 944, 480
OFFSET
0,3
COMMENTS
Modulo 2 binomial transform of nonnegative integers.
LINKS
FORMULA
G.f.: (x/2) * (d/dx) Product_{k>=0} (1 + 2 * x^(2^k)).
a(n) = n * 2^(A000120(n) - 1) = n * A001316(n) / 2.
MAPLE
g:= proc(n, k) local L, M, t, j;
L:= convert(k, base, 2);
M:= convert(n, base, 2);
1-max(zip(`*`, L, M))
end proc:
f:= n -> add(k*g(n-k, k), k=0..n):
map(f, [$0..100]); # Robert Israel, May 24 2020
MATHEMATICA
Table[Sum[Mod[Binomial[n, k], 2] k, {k, 0, n}], {n, 0, 60}]
(* or *)
nmax = 60; CoefficientList[Series[(x/2) D[Product[(1 + 2 x^(2^k)), {k, 0, Log[2, nmax]}], x], {x, 0, nmax}], x]
PROG
(PARI) a(n) = n*2^(hammingweight(n)-1); \\ Michel Marcus, May 22 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, May 21 2020
STATUS
approved