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 A117458 #14 Mar 17 2021 23:44:16 %S A117458 227,313,1723,2003,2311,2609,3329,3701,4007,4027,4801,4931,5107,7253, %T A117458 10457,12143,12163,12211,12433,12547,13063,14143,14341,14831,15139, %U A117458 15373,16091,17027,17047,19403,20047,20261,21059,21149,22157,23053,23293,23431,24229,24623 %N A117458 Primes and their indices such that when their respective SOD's are both prime, the SOD of the index is the nextprime of the prime SOD. %C A117458 "SOD" = "sum of digits". %F A117458 Individually sum the digits of both prime index and associated prime. If both sums are prime and the sum of the index is the next prime of the prime SOD, add to sequence. %e A117458 313 is a term, 65 is the index of the prime 313. The SOD(65) = 11. The SOD(313) = 7. 11 is the next prime after 7. %t A117458 Select[Range[25000], PrimeQ[#] && PrimeQ[Plus @@ IntegerDigits[#]] && %t A117458 NextPrime[Plus @@ IntegerDigits[#]] == Plus @@ IntegerDigits[PrimePi[#]] &] (* _Tanya Khovanova_, Mar 16 2021 *) %Y A117458 Cf. A000720, A007953, A117459, A117460, A117461, A117462, A117463. %K A117458 easy,nonn,base %O A117458 1,1 %A A117458 _Enoch Haga_, Mar 18 2006 %E A117458 Offset changed to 1 by _Alois P. Heinz_, Mar 16 2021