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 A217405 #16 Sep 07 2014 08:15:24 %S A217405 36,28,54,10,87,10,20,1,59,121,97,134,135,88,131,175,58,66 %N A217405 2-adic valuation of A217404. %C A217405 See the main sequence corresponding to this one, A217404. %e A217405 A217404(1)=(2^36)*(7^15), so that the exponent on 2, 36, is the first term here. %o A217405 (PARI) prDigits(n)=my(d=digits(n), v=vector(10)); for(i=1, #d, v[d[i]+1]++); for(i=1, 10, if(!isprime(v[i]), return(0))); 1 %o A217405 list(lim)=my(v=List(), t); for(a=0, log(lim+.5)\log(7), t=7^a; while(t<=lim, if(prDigits(t), listput(v, t)); t<<=1)); apply(k->valuation(k,2),vecsort(Vec(v))) \\ _Charles R Greathouse IV_, Sep 19 2013 %Y A217405 Cf. A217404, A217406. %K A217405 nonn,base %O A217405 1,1 %A A217405 _James G. Merickel_, Oct 02 2012