OFFSET
1,1
COMMENTS
The numbers of terms not exceeding 10^k for k = 3, 4, ..., are 8, 76, 775, 7776, 77845, 778303, 7783285, 77832769, ... Apparently this sequence has an asymptotic density 0.0077832...
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
135 is a term since 135 = 3^3 * 5 and 136 = 2^3 * 17 both have an exponent in their prime factorization which is not a power of 2.
MATHEMATICA
exp2nQ[n_] := AllTrue[FactorInteger[n][[;; , 2]], # == 2^IntegerExponent[#, 2] &]; Select[Range[10^4], ! exp2nQ[#] && ! exp2nQ[# + 1] &]
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Mar 04 2021
STATUS
approved