A161912 a(n) = A040976(n+1) - A006218(n).

0, 0, 0, 0, 1, 1, 1, 1, 1, 4, 2, 6, 4, 4, 4, 6, 7, 7, 7, 9, 5, 7, 7, 11, 11, 12, 10, 10, 6, 8, 14, 16, 16, 14, 20, 18, 15, 19, 19, 21, 19, 19, 21, 21, 19, 15, 23, 33, 27, 26, 24, 26, 22, 30, 28, 30, 28, 26, 28, 30, 20, 28, 38, 36, 31, 31, 37, 41, 45, 43, 39, 43, 39, 43, 45, 43, 43, 47, 43, 49, 49

Offset: 0

Author

Omar E. Pol, Jun 28 2009

Keywords

• easy
• nonn
• less

Crossrefs

Cf. A000005, A001223, A006218, A040976, A161911.

Programs

Maple

A006218 := proc(n) add(floor(n/k),k=1..n) ; end:
A040976 := proc(n) ithprime(n)-2 ; end:
A161912 := proc(n) A040976(n+1)-A006218(n) ;end:
seq(A161912(n),n=0..120) ; # R. J. Mathar, Jul 01 2009

PARI

first(n)=my(v=primes(n+1),s); v[1]-=s=2; forfactored(k=1,n, v[k[1]+1]-=s+=numdiv(k)); v \\ Charles R Greathouse IV, Nov 03 2021

Extensions

Invalid formula deleted and sequence extended by R. J. Mathar, Jul 01 2009