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 A128938 #10 Mar 18 2018 10:36:00 %S A128938 3,5,7,9,10,11,12,13,20,27,28,32,33,35,36,41,42,43,45,47,49,54,63,65, %T A128938 74,75,84,91,94,95,98,104,105,107,109,113,114,117,122,124,126,128,129, %U A128938 135,140,149,152,155,160,164,168,171,189,190,192,199,203,209,212,214,216 %N A128938 Numbers n such that n(n+1) plus the n-th prime is a prime. %e A128938 Given that 23 is the 9th prime, take 9*10 + 23 = 113, a prime. %p A128938 a:=proc(n) if isprime(n*(n+1)+ithprime(n))=true then n else fi end: seq(a(n),n=1..270); # _Emeric Deutsch_, May 05 2007 %t A128938 Select[Range[300],PrimeQ[#(#+1)+Prime[#]]&] (* _Harvey P. Dale_, Mar 18 2018 *) %o A128938 (PARI) isok(n) = isprime(prime(n)+n+n^2); \\ _Michel Marcus_, Mar 13 2016 %Y A128938 Cf. A267421. %K A128938 nonn,less %O A128938 1,1 %A A128938 _J. M. Bergot_, Apr 27 2007 %E A128938 Corrected and extended by _Emeric Deutsch_, May 05 2007