A221858 - OEIS

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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.

2, 3, 7, 5, 11, 13, 19, 29, 31, 41, 37, 43, 47, 61, 59, 67, 71, 23, 17, 73, 79, 89, 109, 103, 53, 107, 113, 139, 151, 127, 137, 83, 167, 173, 181, 191, 101, 193, 223, 233, 211, 199, 229, 251, 239, 281, 277, 241, 131, 269, 263, 283, 313, 311, 349, 163, 317, 337, 331, 307

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OFFSET

1,1

COMMENTS

We conjecture that every term is prime;

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

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

LINKS

Peter J. C. Moses, Table of n, a(n) for n = 1..10000

MATHEMATICA

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

CROSSREFS

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

Sequence in context: A171039 A063904 A297929 * A139317 A117928 A333086

Adjacent sequences: A221855 A221856 A221857 * A221859 A221860 A221861

KEYWORD

nonn,base

AUTHOR

Vladimir Shevelev, Apr 25 2013

EXTENSIONS

More terms from Peter J. C. Moses, Apr 25 2013

STATUS

approved