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 A115656 #8 Oct 06 2014 21:22:59 %S A115656 1,4,8,9,27,72,100,121,144,169,343,400,441,484,576,675,676,800,900, %T A115656 961,1000,1089,1331,1800,2700,3087,4000,7200,7803,8000,9000,9801, %U A115656 10000,10201,10404,10609,12100,12321,12544,12769,14400,14641,14884 %N A115656 Both n and the reverse of n are powerful(1) numbers (A001694). %H A115656 Charles R Greathouse IV, <a href="/A115656/b115656.txt">Table of n, a(n) for n = 1..6228</a> %e A115656 9801=3^4*11^2 and 1089=3^2*11^2. %o A115656 (PARI) is(n)=ispowerful(n) && ispowerful(subst(Polrev(digits(n)),'x,10)) \\ _Charles R Greathouse IV_, Sep 16 2014 %o A115656 (PARI) has(n)=ispowerful(subst(Polrev(digits(n)),'x,10)) %o A115656 list(lim)=my(v=List(),t,t2); for(m=1,lim^(1/3), t=m^3; for(n=1,sqrtint(lim\t), if(has(t2=t*n^2), listput(v,t2)))); Set(v) \\ _Charles R Greathouse IV_, Sep 16 2014 %Y A115656 Cf. A001694, A115655, A085751. %K A115656 base,nonn %O A115656 1,2 %A A115656 _Giovanni Resta_, Jan 28 2006