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 A139107 #5 Oct 03 2015 23:15:13 %S A139107 1,9,599,38359,2454999,628479869,643563386359,41188056726999, %T A139107 168706280353789919,43188807770570219359,2764083697316494039005, %U A139107 2830421706052089895941623,46373629231957440855107559295 %N A139107 Bisection of A139102. %p A139107 A139101 := proc(n) option remember ; local a,p; if n = 1 then RETURN(1); else a := 10*A139101(n-1) ; for p from ithprime(n-1)+1 to ithprime(n)-1 do a := 10*a+1 ; od: fi ; RETURN(a) ; end: bin2dec := proc(n) local nshft ; nshft := convert(n,base,10) ; add(op(i,nshft)*2^(i-1),i=1..nops(nshft) ) ; end: A139102 := proc(n) bin2dec(A139101(n)) ; end: A139107 := proc(n) A139102(2*n-1) ; end: seq(A139107(n),n=1..35) ; # _R. J. Mathar_, Apr 25 2008 %Y A139107 Cf. A139102. %K A139107 nonn %O A139107 1,2 %A A139107 _Omar E. Pol_, Apr 08 2008 %E A139107 More terms from _R. J. Mathar_, Apr 25 2008