A387122 - OEIS

A387122

Greatest prime divisor of 2*prime(n) + 3.

7, 3, 13, 17, 5, 29, 37, 41, 7, 61, 13, 11, 17, 89, 97, 109, 11, 5, 137, 29, 149, 23, 13, 181, 197, 41, 19, 31, 17, 229, 257, 53, 277, 281, 43, 61, 317, 47, 337, 349, 19, 73, 11, 389, 397, 401, 17, 449, 457, 461, 67, 37, 97, 101, 47, 23, 541, 109, 557, 113, 569, 31

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..62.

FORMULA

a(n) = A006530(A129069(n)).

EXAMPLE

a(1) = Gpf(2*2+3) = Gpf(7) = 7.

a(2) = Gpf(2*3+3) = Gpf(9) = 3.

MAPLE

f:= n -> max(numtheory:-factorset(2*ithprime(n)+3)):