A211188 - OEIS

%I #15 Jun 25 2024 01:30:49

%S 0,2,2,4,5,2,5,6,2,13,5,17,3,12,11,15,9,6,21,11,6,7,3,7,7,18,7,10,6,

%T 14,11,7,6,29,2,6,22,10,10,6,16,12,6,5,11,15,6,24,12,13,19,21,15,45,3,

%U 17,6,11,24,15,9,9,6,28,3,7,7,26,10,55,14,21,24,8

%N a(n) is the number of distinct prime divisors among all the composites of the form k^2 + 1 between the two primes A002496(n) and A002496(n+1).

%C a(1)=0; for n > 1, a(n) = number of elements of each row in A211175(n).

%H Michel Lagneau, <a href="/A211188/b211188.txt">Table of n, a(n) for n = 1..10000</a>

%p with(numtheory) :lst:={}: for n from 2 to 600 do:p:=n^2+1:x:=factorset(p):lst:=lst union x:if type(p,prime)=true then m:=nops(lst minus {p}): printf(`%d, `,m):lst:={}:else fi:od:

%Y Cf. A002144, A002496, A002522, A134406, A181413, A206400, A211175.

%K nonn

%O 1,2

%A _Michel Lagneau_, Feb 03 2013