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 A230006 #14 Jan 04 2025 15:42:58
%S A230006 1,37,225,397,11112722,1309286244182
%N A230006 Numbers k such that sigma(k) + phi(k) = reversal(k) + 1.
%C A230006 If p = 4*10^m-3 is prime then p is in the sequence.
%C A230006 a(7) > 10^13. - _Giovanni Resta_, Feb 08 2014
%e A230006 sigma(37)+phi(37) = 38+36 = 73+1 = reversal(37)+1.
%t A230006 r[n_] := FromDigits[Reverse[IntegerDigits[n]]]; Do[If[DivisorSigma[1, n] + EulerPhi[n] == r[n]+1, Print[n]], {n, 1000000000}]
%Y A230006 Cf. A000010, A000203, A004086, A101398, A230004, A230005.
%K A230006 nonn,base,more
%O A230006 1,2
%A A230006 _Farideh Firoozbakht_, Dec 02 2013
%E A230006 a(6) from _Giovanni Resta_, Feb 06 2014