A122825 a(n) = n + number of previous prime terms, a(1) = 1.

1, 2, 4, 5, 7, 9, 10, 11, 13, 15, 16, 17, 19, 21, 22, 23, 25, 26, 27, 28, 29, 31, 33, 34, 35, 36, 37, 39, 40, 41, 43, 45, 46, 47, 49, 50, 51, 52, 53, 55, 56, 57, 58, 59, 61, 63, 64, 65, 66, 67, 69, 70, 71, 73, 75, 76, 77, 78, 79, 81, 82, 83, 85, 86, 87, 88, 89, 91, 92, 93, 94

Offset: 1

Author

Zak Seidov, Oct 23 2006

Keywords

• nonn

Comments

Or, a(1)=1; a(n)=a(n-1) + d: if a(n-1) is prime then d=2 otherwise d=1.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A135731 (complement).

Programs

Mathematica

s={1};p=0;Do[b=n+p;AppendTo[s,b];If[PrimeQ[b],p++ ],{n,2,130}];s

PARI

lista(nn) = {print1(a=1, ", "); nbp = 0; for (n=2, nn, newn = nbp + n; print1(newn, ", "); nbp += isprime(newn););} \\ Michel Marcus, Jul 31 2017