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 A133229 #8 Jun 18 2021 16:07:36 %S A133229 -1,2,8,14,20,27,37,46,57,70,80,95,108,124,142,160,174,193,213,231, %T A133229 253,277,297,321,346,376,396,425,451,476,507,537,566,598,626,659,693, %U A133229 725,770,796,836,870,912,941,984,1022,1060,1103,1146,1187,1243,1277,1322,1366,1404,1449,1500,1553,1597,1648,1691,1746,1798 %N A133229 Smallest index-sum i+j such that prime(i) + prime(j) = 4*n^2. a(0)=-1 to indicate that there is no such pair of primes. %F A133229 a(n)= min(i+j), 1<=i<=j: A000040(i)+A000040(j)=A016742(n). - _R. J. Mathar_, Apr 22 2008 %p A133229 A133229 := proc(n) local a016742,i,j,a ; a016742 := 4*n^2 ; a := 2*numtheory[pi](a016742) ; if n =0 then RETURN(-1) ; fi ; for i from 1 to numtheory[pi](a016742-1) do if isprime(a016742-ithprime(i)) then j := numtheory[pi](a016742-ithprime(i)) : a := min(a,i+j) ; fi ; od: RETURN(a) ; end: seq(A133229(n),n=0..80) ; # _R. J. Mathar_, Apr 22 2008 %t A133229 Join[{-1},Table[Min[Total/@(PrimePi/@Select[IntegerPartitions[4 n^2, {2}],AllTrue[ #,PrimeQ]&])],{n,70}]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Jun 18 2021 *) %Y A133229 Cf. A000040, A005843, A016742, A113631, A133230. %K A133229 sign %O A133229 0,2 %A A133229 _Alexander R. Povolotsky_, Dec 19 2007 %E A133229 Edited and extended by _R. J. Mathar_, Apr 22 2008