A221858 - OEIS

A221858

a(1)=2, a(2)=3, for n>=3, a(n) is the n-th number which is obtained by application of Eratosthenes-like sieve (with removing 1's) to sequence: odd part of digit sum of 2^m, m>=1.

%I #33 Dec 14 2014 15:10:45

%S 2,3,7,5,11,13,19,29,31,41,37,43,47,61,59,67,71,23,17,73,79,89,109,

%T 103,53,107,113,139,151,127,137,83,167,173,181,191,101,193,223,233,

%U 211,199,229,251,239,281,277,241,131,269,263,283,313,311,349,163,317,337,331,307

%N a(1)=2, a(2)=3, for n>=3, a(n) is the n-th number which is obtained by application of Eratosthenes-like sieve (with removing 1's) to sequence: odd part of digit sum of 2^m, m>=1.

%C We conjecture that every term is prime;

%C moreover, we conjecture that the sequence is a permutation of the sequence of all primes.

%C For comparison, if in the definition we replace 2^m with 13^m, then we obtain a sequence containing 25. - _Vladimir Shevelev_, Dec 07 2014

%H Peter J. C. Moses, <a href="/A221858/b221858.txt">Table of n, a(n) for n = 1..10000</a>

%t Flatten[{{2,3},DeleteDuplicates[Select[Map[#/(2^IntegerExponent[#,2])&[Total[IntegerDigits[2^#]]]&,Range[3,300]],PrimeQ]]}] (* _Peter J. C. Moses_, Apr 25 2013 *)

%Y Cf. A000040, A225017, A225039, A225040, A225093.

%K nonn,base

%O 1,1

%A _Vladimir Shevelev_, Apr 25 2013

%E More terms from _Peter J. C. Moses_, Apr 25 2013