cp's OEIS Frontend

A022332 Exponent of 2 (value of i) in n-th number of form 2^i*5^j.

%I A022332 #22 Feb 07 2020 09:03:19
%S A022332 0,1,2,0,3,1,4,2,0,5,3,1,6,4,2,0,7,5,3,1,8,6,4,2,9,0,7,5,3,10,1,8,6,4,
%T A022332 11,2,9,0,7,5,12,3,10,1,8,6,13,4,11,2,9,0,7,14,5,12,3,10,1,8,15,6,13,
%U A022332 4,11,2,9,16,0,7,14,5,12,3,10,17,1,8,15,6,13,4,11,18,2,9,16,0,7,14,5,12,19,3,10
%N A022332 Exponent of 2 (value of i) in n-th number of form 2^i*5^j.
%H A022332 Amiram Eldar, <a href="/A022332/b022332.txt">Table of n, a(n) for n = 1..10000</a>
%F A022332 a(n) = A007814(A003592(n)). - _Amiram Eldar_, Feb 07 2020
%p A022332 A022332 := proc(n)
%p A022332     A007814(A003592(n)) ;
%p A022332 end proc:
%p A022332 seq(A022332(n),n=1..20) ; # _R. J. Mathar_, Aug 04 2016
%t A022332 s = {}; m = 12; Do[n = 5^k; While[n <= 5^m, AppendTo[s, n]; n *= 2], {k, 0, m}]; IntegerExponent[#, 2] & /@ Union[s]
%o A022332 (PARI) lista(nn) = {vec = vector(nn, i , i); subset = select(n->(n/(2^valuation(n,2)*5^valuation(n,5)) == 1), vec); for (i = 1, #subset, print1(valuation(subset[i], 2), ", "););} \\ _Michel Marcus_, Oct 01 2013
%Y A022332 Cf. A003592, A007814, A022333.
%K A022332 nonn
%O A022332 1,3
%A A022332 _Clark Kimberling_
%E A022332 Corrected by _David W. Wilson_, Oct 15 1997