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%I #9 Apr 30 2021 11:42:13
%S 0,1,0,2,1,1,3,1,2,2,2,5,2,3,2,6,5,5,6,5,5,5,6,8,4,4,4,8,6,8,6,9,10,9,
%T 5,10,7,10,9,11,9,8,11,5,11,4,10,14,9,19,9,14,9,11,11,9,9,15,15,17,10,
%U 11,13,15,8,15,12,17,15,10,13,15,14,17,12,13,12,16,13,13,18,16,18,15,15,17
%N a(n) is the number of distinct primes of the form A007504(n) mod p for the first n primes p.
%H Robert Israel, <a href="/A343796/b343796.txt">Table of n, a(n) for n = 1..10000</a>
%e a(8) = 1 because A007504(8) = 77 and there is only one prime of the form 77 mod p for the first 8 primes p, namely 2 = 77 mod 3 = 77 mod 5.
%p N:= 200: # for a(1)..a(N)
%p P:= [seq(ithprime(i),i=1..N)]:
%p S:= ListTools:-PartialSums(P):
%p PS:= convert(P,set):
%p f:= proc(n)
%p nops(map(p -> S[n] mod p, PS[1..n]) intersect PS);
%p end proc:
%p map(f, [$1..N]);
%Y Cf. A007504, A343798.
%K nonn
%O 1,4
%A _J. M. Bergot_ and _Robert Israel_, Apr 29 2021