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 A237257 #19 Jul 14 2021 01:55:58 %S A237257 1863,1979883,126639495,162037386,1979999883,1061283473946 %N A237257 Numbers k such that phi(k) = reversal(sigma(k)) - sigma(k). %C A237257 If p = (22*10^m - 13)/9 is prime, then 3^4*p is a term of the sequence. This happens for m = 1, 4, 7, 12, 30, 94, 178, 196, 564, ... . %C A237257 a(7) > 3*10^12. %C A237257 If k is in the sequence A102953 then p = (22*10^k - 13)/9 is prime. 9 divides all known terms; is it true for all terms of this sequence? - _Farideh Firoozbakht_, Feb 06 2014 %e A237257 k = 1979999883 = 3^4*24444443 is a term, since sigma(k) = 2957777724 and 4277777592 - 2957777724 = 1319999868 = phi(k). %Y A237257 Cf. A102953, A230012. %K A237257 nonn,base,more %O A237257 1,1 %A A237257 _Giovanni Resta_, Feb 05 2014