A076565 - OEIS

A076565

Greatest prime divisor of 2n+1 (sum of two successive integers).

3, 5, 7, 3, 11, 13, 5, 17, 19, 7, 23, 5, 3, 29, 31, 11, 7, 37, 13, 41, 43, 5, 47, 7, 17, 53, 11, 19, 59, 61, 7, 13, 67, 23, 71, 73, 5, 11, 79, 3, 83, 17, 29, 89, 13, 31, 19, 97, 11, 101, 103, 7, 107, 109, 37, 113, 23, 13, 17, 11, 41, 5, 127, 43, 131, 19, 5, 137, 139, 47, 13

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OFFSET

1,1

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A006530(2n+1). - Robert Israel, Mar 17 2017

MAPLE

seq(max(numtheory:-factorset(2*n+1)), n=1..200); # Robert Israel, Mar 17 2017

MATHEMATICA

Table[FactorInteger[2n + 1][[-1, 1]], {n, 1, 100}] (* Indranil Ghosh, Mar 20 2017 *)

PROG