A085608 Index of the smallest prime starting with n.

5, 1, 2, 13, 3, 18, 4, 23, 25, 26, 5, 31, 6, 35, 36, 38, 7, 42, 8, 304, 47, 48, 9, 53, 54, 56, 58, 60, 10, 63, 11, 453, 67, 69, 71, 73, 12, 76, 78, 79, 13, 82, 14, 86, 88, 89, 15, 93, 94, 96, 682, 98, 16, 100, 102, 103, 105, 107, 17, 110, 18, 807

Offset: 1

Author

Zak Seidov, Jul 07 2003

Keywords

• easy
• base
• nonn

Examples

			a(4)=13 because prime[13]=41 is the smallest prime starting with 4.
		

Crossrefs

Cf. A000720, A018800.

Formula

a(n) = PrimePi(A018800(n)). - Michel Marcus, Oct 19 2013