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 A375545 #16 Jul 25 2025 09:00:45
%S A375545 1,2,4,14,6,34,101,111,174,42,300,21,340,3238,1652,2049,3345,5354,
%T A375545 6676,7322,12037,30205,51733,7357,99091,167580,2967,15042,2354,193,
%U A375545 25884,126695,232179,234477,11370,37546,176867,28678,3270,578,84666,966,284,349823,2645
%N A375545 Indices of the Sylvester primes (A375543) in the primes (A000040).
%F A375545 a(n) = A000720(A375543(n)).
%e A375545 a(7) = 101 because A375543(7) = 547 = A000040(101).
%t A375545 Module[{nmax = 20, a = {}, p = 1, f}, Do[p *= p + 1; f = 2; While[MemberQ[a, f] || !Divisible[p, f], f = NextPrime[f]]; AppendTo[a, f], nmax]; PrimePi[a]] (* _Paolo Xausa_, Sep 09 2024 *)
%Y A375545 Cf. A000040, A000720, A375543.
%K A375545 nonn
%O A375545 1,2
%A A375545 _Peter Luschny_, Sep 05 2024
%E A375545 More terms from _Jinyuan Wang_, Jul 25 2025