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A255488
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Number of odd terms in expansion of (1 + x + x^2 + x^3 + x^4 + x^5)^n.
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7
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1, 6, 6, 12, 6, 16, 12, 24, 6, 36, 16, 32, 12, 36, 24, 48, 6, 36, 36, 72, 16, 56, 32, 64, 12, 72, 36, 72, 24, 68, 48, 96, 6, 36, 36, 72, 36, 96, 72, 144, 16, 96, 56, 112, 32, 100, 64, 128, 12, 72, 72, 144, 36, 120, 72, 144, 24, 144, 68, 136
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OFFSET
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0,2
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COMMENTS
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LINKS
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EXAMPLE
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Written as an irregular triangle in which the row lengths are the terms of A011782, the sequence begins:
1;
6;
6,12;
6,16,12,24;
6,36,16,32,12,36,24,48;
6,36,36,72,16,56,32,64,12,72,36,72,24,68,48,96;
6,36,36,72,36,96,72,144,16,96,56,112,32,100,64,128,12,72,72,144,36,120,72,144,24,144,68,136...
...
In each row the first quarter of the terms (and no more) are equal to 6 times the beginning of the sequence itself (corrected after Sloane's comment in A247649, Mar 03 2015).
(End)
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MAPLE
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r1:=proc(f) local g, n; g:=n->nops(expand(f^n) mod 2); [seq(g(n), n=0..90)]; end;
r1(1+x+x^2+x^3);
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MATHEMATICA
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a[n_] := Count[CoefficientList[(1 + x + x^2 + x^3 + x^4 + x^5)^n, x], _?OddQ];
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PROG
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(PARI) a(n) = {my(pol=(1+x+x^2+x^3+x^4+x^5)*Mod(1, 2)); subst(lift(pol^n), x, 1); } \\ Michel Marcus, Mar 01 2015
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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