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 A175154 #3 Sep 08 2022 08:45:51 %S A175154 5,6,7,9,11,13,16,19,23,26,39,44,54,61,66,71,83,103,121,143,152,160, %T A175154 197,238,248,270,313,336,386,403,453,481,512,527,542,619,635,714,752, %U A175154 804,842,857,898,915,933,1092,1112,1154,1242,1265,1307,1372,1412,1534,1561 %N A175154 a(n) = prime index of A048059(n). %C A175154 Indices of primes of the form n^2+n+11. %C A175154 PrimePi(A048059(n)), where PrimePi(k) is the number of primes <= k (A000720). %C A175154 prime(a(n)) = A048059(n). %F A175154 a(n) = A000720(A048059(n)). %e A175154 A048059(7) = 53 is the seventh prime of the form n^2+n+11; 53 has prime index 16 (PrimePi(53) = 16, prime(16) = 53). Hence a(7) = 16. %o A175154 (Magma) PrimePi:=func< n | #PrimesUpTo(n) >; [ PrimePi(p): x in [0..120] | IsPrime(p) where p is x^2+x+11 ]; %Y A175154 Cf. A048058 (n^2+n+11), A048097 (n such that n^2+n+11 is prime), A048059 (primes of the form n^2+n+11), A000720 (PrimePi(n), number of primes <= n), A173752. %K A175154 nonn %O A175154 1,1 %A A175154 _Klaus Brockhaus_, Feb 27 2010