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Total number of 1-s in binary representation of all factorials from 1 to n.
1

%I #25 Nov 13 2024 16:42:58

%S 1,2,4,6,10,14,20,26,32,43,50,62,74,86,104,122,144,167,184,206,231,

%T 259,290,319,349,384,422,464,504,552,594,636,682,733,789,840,898,957,

%U 1021,1084,1150,1214,1285,1359,1429,1506,1587,1676,1763,1852,1942,2030,2124

%N Total number of 1-s in binary representation of all factorials from 1 to n.

%H Harvey P. Dale, <a href="/A071425/b071425.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = Sum_{i=1..n} A079584(i).

%t s=0; Do[s=s+Apply[Plus, IntegerDigits[n!, 2]]; Print[s], {n, 1, 128}]

%t Accumulate[DigitCount[Range[60]!,2,1]] (* _Harvey P. Dale_, Apr 18 2014 *)

%o (Python)

%o def A071425(n):

%o c, a = 0, 1

%o for i in range(1,n+1):

%o c += (a:=a*i).bit_count()

%o return c # _Chai Wah Wu_, Nov 12 2024

%Y Cf. A000142, A000788.

%Y Partial sums of A079584 starting at index 1.

%K base,easy,nonn,changed

%O 1,2

%A _Labos Elemer_, May 27 2002