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 A167501 #3 Jul 14 2012 11:32:32 %S A167501 1,1,0,1,0,0,1,1,1,1,0,0,0,1,0,0,1,1,0,1,0,1,1,1,0,1,0,0,0,1,1,0,0,1, %T A167501 0,1,0,1,0,0,1,0,1,1,0,1,0,1,1,1,1,1,0,0,0,1,1,0,1,0,1,1,1,1,0,1,1,1, %U A167501 1,1,1,0,0,0,1,0,1,0,0,1,0,0,1,0,0,1,1,0,1,0,1,0,0,1,1,0,1,0,1,1,1,0,1,1,0 %N A167501 Sequence of bits in A167500 (= list of nonzero bits in this sequence, when written in binary). %C A167501 Sequence A167500 starts 1,2,4,7,... = 1,10,100,111,.... when written in binary (A167502). This sequence lists the bits one by one, MSB first: 1,1,0,1,0,0,1,1,1,...; by definition A167500 lists the nonzero terms of this function, and reciprocally this sequence is the characteristic function of A167500. %o A167501 (PARI) a=b=[]; for(n=1,30, #b >= n & for( i=a[n-1]+1,#b, b[i] & (a=concat(a,i)) & break); #a<n & a=concat(a,#b+1); b=concat(b,binary( a[n] ))); b %Y A167501 Cf. A167500 (lists nonzero terms in this sequence), A167502. %K A167501 base,nonn %O A167501 1,1 %A A167501 _M. F. Hasler_, Nov 05 2009