login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A137722 Number of numbers not greater than n with exactly one prime gap in their factorization. 3
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,14

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.

Sequence in context: A103374 A208251 A241087 * A081305 A035665 A307833

Adjacent sequences:  A137719 A137720 A137721 * A137723 A137724 A137725

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Feb 09 2008

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 3 02:14 EST 2021. Contains 349445 sequences. (Running on oeis4.)