%I #8 Oct 09 2017 12:45:20
%S 23,31,38,52,54,62,84,93,98,111,118,135,150,201,209,215,228,258,266,
%T 288,299,330,348,352,379,399,400,471,476,479,488,500,509,511,533,538,
%U 540,545,560,585,598,618,624,629,678,693,714,720,751,752,759,771,790,805
%N Numbers n such that sum of digits of the n-th prime = the sum of digits of the n-th semiprime.
%H Harvey P. Dale, <a href="/A169640/b169640.txt">Table of n, a(n) for n = 1..1000</a>
%F A007605(a(n))=A175013(a(n)).
%F A007953(A000040(n)) = A007953(A001358(n)). - Chandler
%e a(1)=23 because 23rd prime=83(8+3=11) and 23rd semiprime=65(6+5=11).
%t Module[{nn=900,sps},sps=Take[Select[Range[4nn],PrimeOmega[#]==2&],nn];Position[Thread[{Prime[Range[nn]],sps}],_?(Total[IntegerDigits[#[[1]]]] == Total[IntegerDigits[#[[2]]]]&),1,Heads->False]]//Flatten (* _Harvey P. Dale_, Oct 09 2017 *)
%Y Cf. A007605, A175013.
%K nonn,base,less
%O 1,1
%A _Juri-Stepan Gerasimov_, Apr 04 2010
%E Edited by _N. J. A. Sloane_, Apr 05 2010
%E Edited, corrected and extended by _Ray Chandler_, Apr 05 2010
|