A284890 a(1)=2, and then a(n+1) = a(n) + k where prime(k) is the least prime dividing a(n).

2, 3, 5, 8, 9, 11, 16, 17, 24, 25, 28, 29, 39, 41, 54, 55, 58, 59, 76, 77, 81, 83, 106, 107, 135, 137, 170, 171, 173, 213, 215, 218, 219, 221, 227, 276, 277, 336, 337, 405, 407, 412, 413, 417, 419, 500, 501, 503, 599, 708, 709, 836, 837, 839, 985, 988, 989

Offset: 1

Author

Rémy Sigrist, Apr 05 2017

Keywords

• nonn

Examples

			a(9) = 24 = prime(1)^3*prime(2), hence a(10) = 24+1 = 25.
a(14) = 41 = prime(13), hence a(15) = 41+13 = 54.
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..2297
• Rémy Sigrist, C program for A284890

Crossrefs

Cf. A055396, A076271.

Programs

Mathematica

NestList[#+PrimePi[FactorInteger[#][[1,1]]]&,2,60] (* Harvey P. Dale, May 08 2022 *)

Formula

a(n+1) = a(n) + A055396(a(n)) for any n>1.