A072580 - OEIS

%I #4 Mar 30 2012 18:50:24

%S 11,13,71,79,89,107,127,131,139,157,179,181,227,229,331,337,419,421,

%T 433,457,461,487,491,787,797,809,811,821,823,853,877,919,977,1163,

%U 1181,1213,1223,1231,1277,1279,1459,1487,1523,1667,1697,1733,1741,1861,1867

%N A000040(A072577(n)).

%e In binary representation 20 and A000040(20)=71 have three 0's: 13='10100' and 71='1000111', therefore 71 is a term.

%Y Cf. A072581, A072582, A072439, A072584.

%Y A023416(a(n))=A023416(A072577(n))=A035103(n).

%K nonn

%O 1,1

%A _Reinhard Zumkeller_, Jun 23 2002