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A188064
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Partial sums of wt(n)! where wt(n) is the Hamming weight of n (A000120).
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1
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1, 2, 3, 5, 6, 8, 10, 16, 17, 19, 21, 27, 29, 35, 41, 65, 66, 68, 70, 76, 78, 84, 90, 114, 116, 122, 128, 152, 158, 182, 206, 326, 327, 329, 331, 337, 339, 345, 351, 375, 377, 383, 389, 413, 419, 443, 467, 587, 589, 595, 601, 625, 631, 655, 679, 799, 805, 829, 853, 973, 997, 1117
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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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FORMULA
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a(n)=sum(k=0,n,wt(k)!) where wt(k) is the Hamming weight of k.
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MATHEMATICA
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FoldList[Plus, 0!, Table[(Plus @@ IntegerDigits[n, 2])!, {n, 1, 70}]] (* From Olivier Gérard, Mar 23 2011 *)
Accumulate[DigitCount[Range[0, 70], 2, 1]!] (* Harvey P. Dale, Jun 26 2013 *)
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PROG
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(PARI)
bitcount(x)=
{ /* Return Hamming weight of x */
local(p); p = 0;
while ( x, p+=bitand(x, 1); x>>=1; );
return( p );
}
N=65; /* that many terms */
f=vector(N, n, bitcount(n-1)!); /* factorials of Hamming weights */
s=vector(N); s[1]=f[1]; /* for cumulative sums */
for (n=2, N, s[n]=s[n-1]+f[n]); /* sum up */
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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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