A049847 a(n) = (2*n + 1 - prevprime(2*n+1))/2.

1, 1, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 3, 1, 1, 2, 3, 1, 2, 1, 1, 2, 1, 2, 3, 1, 2, 3, 1, 1, 2, 3, 1, 2, 1, 1, 2, 3, 1, 2, 1, 2, 3, 1, 2, 3, 4, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 3, 4, 5, 6, 7, 1, 2, 1, 2, 3, 1, 1, 2, 3, 4, 5, 1, 1, 2, 3, 1, 2, 3, 1, 2, 1, 2, 3, 1, 2, 3, 1, 1, 2, 3, 4

Offset: 2

Author

N. J. A. Sloane

Keywords

• nonn

Crossrefs

Cf. A049613, A049653, A049711, A049716.

Programs

Mathematica

Table[(2n+1-NextPrime[2n+1,-1])/2,{n,2,100}] (* Harvey P. Dale, Jul 25 2015 *)