OFFSET
1,1
COMMENTS
First differs from its subsequence A138302 \ {1} at n = 378: a(378) = 432 = 2^4 * 3^3 is not a term of A138302.
First differs from A096432, A220218 \ {1}, A335275 \ {1} and A337052 \ {1} at n = 56, and from A270428 \ {1} at n = 113.
Numbers k such that A051903(k) is a power of 2.
The asymptotic density of this sequence is 1/zeta(3) + Sum_{k>=2} (1/zeta(2^k+1) - 1/zeta(2^k)) = 0.87442038669659566330... .
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
MATHEMATICA
pow2Q[n_] := n == 2^IntegerExponent[n, 2];
Select[Range[2, 100], pow2Q[Max[FactorInteger[#][[;; , 2]]]] &]
Select[Range[2, 80], IntegerQ[Log2[Max[FactorInteger[#][[;; , 2]]]]]&] (* Harvey P. Dale, Nov 06 2024 *)
PROG
(PARI) ispow2(n) = n >> valuation(n, 2) == 1;
is(n) = n > 1 && ispow2(vecmax(factor(n)[, 2]));
CROSSREFS
KEYWORD
nonn,easy,changed
AUTHOR
Amiram Eldar, Feb 06 2024
STATUS
approved