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%I #22 Dec 19 2018 15:07:06
%S 1,7,13,5,7,11,7,25,31,7,43,49,37,13,29,1,13,29,73,79,19,41,97,85,73,
%T 97,7,91,133,121,59,115,103,127,71,157,17,115,65,17,71,37,17,169,175,
%U 163,187,175,17,89,23,217,49,55,217,107,211,181,241,211,199,205
%N The odd part of the digit sum of 7^n.
%C Conjecture: the sequence contains all primes > 3.
%H Peter J. C. Moses, <a href="/A225091/b225091.txt">Table of n, a(n) for n = 0..1999</a>
%F a(n) = A000265(A066003(n)). - _R. J. Mathar_, May 05 2013
%p read(transforms) :
%p A225091 := proc(n)
%p A000265(digsum(7^n)) ;
%p end proc: # _R. J. Mathar_, May 05 2013
%t Map[#/(2^IntegerExponent[#,2])&[Total[IntegerDigits[7^#]]]&, Range[0,99]] (* _Peter J. C. Moses_, Apr 27 2013 *)
%o (PARI) a(n) = my(s = sumdigits(7^n)); s >> valuation(s, 2); \\ _Michel Marcus_, Dec 19 2018
%Y Cf. A221858, A225017, A225039, A225040.
%K nonn,base
%O 0,2
%A _Vladimir Shevelev_, Apr 27 2013
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