A137722 Number of numbers not greater than n with exactly one prime gap in their factorization.

0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 3, 4, 5, 5, 5, 5, 6, 6, 7, 7, 7, 7, 7, 8, 9, 9, 9, 9, 10, 11, 12, 12, 13, 13, 14, 14, 15, 15, 15, 15, 16, 17, 18, 18, 18, 19, 20, 21, 22, 22, 22, 22, 23, 24, 24, 25, 26, 26, 27, 28, 29, 29, 29, 29, 30, 30, 31, 31, 32, 32, 33, 33, 34

Offset: 1

Author

Reinhard Zumkeller, Feb 09 2008

Keywords

• nonn

Comments

a(n) > a(n-1) iff A073490(n) = 1;

A137721(n) > a(n) for n < 134;

A137721(n) < a(n) for n > 140.

Links

• R. Zumkeller, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A073493.