A059292 a(n) = n + 2 - (number of divisors of n).

2, 2, 3, 3, 5, 4, 7, 6, 8, 8, 11, 8, 13, 12, 13, 13, 17, 14, 19, 16, 19, 20, 23, 18, 24, 24, 25, 24, 29, 24, 31, 28, 31, 32, 33, 29, 37, 36, 37, 34, 41, 36, 43, 40, 41, 44, 47, 40, 48, 46, 49, 48, 53, 48, 53, 50, 55, 56, 59, 50, 61, 60, 59, 59, 63, 60, 67

Offset: 1

Author

N. J. A. Sloane, Jan 25 2001

Keywords

• nonn

References

• L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 121, see #17.

Links

• Harry J. Smith, Table of n, a(n) for n = 1..5000

Crossrefs

Cf. A000005, A049820, A062968. - Omar E. Pol, Jul 16 2009

Programs

Magma

[n+2-DivisorSigma(0, n): n in [1..100]]; // Vincenzo Librandi, Jan 05 2017

Mathematica

Table[n + 2 - DivisorSigma[0, n], {n,1,100}] (* G. C. Greubel, Jan 04 2017 *)

PARI

a(n) = { n + 2 - numdiv(n) } \\ Harry J. Smith, Jun 25 2009

Formula

a(n) = n + 2 - A000005(n) = A049820(n) + 2. - Omar E. Pol, Jul 16 2009