A375545 - OEIS

%I #16 Jul 25 2025 09:00:45

%S 1,2,4,14,6,34,101,111,174,42,300,21,340,3238,1652,2049,3345,5354,

%T 6676,7322,12037,30205,51733,7357,99091,167580,2967,15042,2354,193,

%U 25884,126695,232179,234477,11370,37546,176867,28678,3270,578,84666,966,284,349823,2645

%N Indices of the Sylvester primes (A375543) in the primes (A000040).

%F a(n) = A000720(A375543(n)).

%e a(7) = 101 because A375543(7) = 547 = A000040(101).

%t 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 Cf. A000040, A000720, A375543.

%K nonn

%O 1,2

%A _Peter Luschny_, Sep 05 2024

%E More terms from _Jinyuan Wang_, Jul 25 2025