A077067 Squarefree numbers of the form prime + 1.

3, 6, 14, 30, 38, 42, 62, 74, 102, 110, 114, 138, 158, 174, 182, 194, 230, 258, 278, 282, 314, 318, 354, 374, 390, 398, 402, 410, 422, 434, 458, 462, 510, 542, 570, 602, 614, 618, 642, 654, 662, 674, 678, 710, 734, 758, 762, 770, 798, 822, 830, 854, 858, 878

Offset: 1

Author

Reinhard Zumkeller, Oct 23 2002

Keywords

• nonn

Examples

			A005117(28) = 42 = 2*3*7 is a term as 42 = A000040(13) + 1 = 41+1.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000040, A005117, A008864, A049097, A077064, A077066.

Programs

Mathematica

Select[Prime[Range[200]]+1,SquareFreeQ] (* Harvey P. Dale, Aug 20 2017 *)

PARI

isok(n) = issquarefree(n) && isprime(n-1); \\ Michel Marcus, Mar 22 2016

PARI

lista(nn) = forprime(p=2, nn, if (issquarefree(p+1), print1(p+1, ", "))); \\ Michel Marcus, Mar 22 2016

Formula

A077066(a(n)) = a(n).

a(n) = A049097(n)+1. - Zak Seidov, Aug 15 2006