This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A178043 #11 Jun 22 2014 02:00:32 %S A178043 1,3,3,4,10,14,11,12,15,16,18,19,15,18,24,31,29,36,49,42,43,56,44,34, %T A178043 39,42,47,50,51,66,70,72,73,88,71,104,94,97,112,100,101,116,101,77,78, %U A178043 71,72,87,89,90,99,102,131,105,96,99,107,108,155,129,159,138,131,132,147 %N A178043 n-th semiprime minus number of distinct transpositions of digits (zeros and units) in n-th semiprime written in base 2. %H A178043 Vincenzo Librandi, <a href="/A178043/b178043.txt">Table of n, a(n) for n = 1..1000</a> %F A178043 a(n)=s-binomial((A000120(s)+A023416(s)), A000120(s)), where s=semiprime(n). %t A178043 #-Length[Permutations[IntegerDigits[#,2]]]&/@Select[Range[ 2,300], PrimeOmega[ #] == 2&] (* _Harvey P. Dale_, Jun 21 2014 *) %Y A178043 Cf. A001358, A122466. %K A178043 nonn,base %O A178043 1,2 %A A178043 _Juri-Stepan Gerasimov_, May 17 2010 %E A178043 More terms from _R. J. Mathar_, May 28 2010