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 A217408 #11 Sep 07 2014 08:34:31 %S A217408 35,20,59,42,63,5,69,73,21,43,71,1149 %N A217408 3-adic valuation of A217407. %C A217408 See main sequence for rationale. %e A217408 The first number that has only 3 and 5 as prime factors and has prime counts of each digit 0-9 in its decimal representation is (3^35)*(5^17), so, corresponding to that being A217407(1), this sequence's first term is 35. %o A217408 (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 A217408 list(lim)=my(v=List(), t); for(a=0, log(lim+.5)\log(5), t=5^a; while(t<=lim, if(prDigits(t), listput(v, t)); t*=3)); apply(k -> valuation(k,3), vecsort(Vec(v))) \\ _Charles R Greathouse IV_, Sep 19 2013 %Y A217408 Cf. A217407, A217409. %K A217408 nonn,base,less %O A217408 1,1 %A A217408 _James G. Merickel_, Oct 02 2012