A080287 Successively larger gaps in Ulam numbers start at this Ulam number.

1, 4, 8, 18, 38, 87, 114, 155, 282, 751, 949, 1257, 1553, 1858, 2178, 4800, 5384, 18796, 37562, 64420, 252719, 933709, 289738117, 332250401, 667752899, 699497052, 966290117, 224582902442, 319654121875, 418843012121, 802386465583

Offset

1,2

Comments

The gaps are in A080288.

References

D. E. Knuth, The Art of Computer Programming, vol 4A, section 7.1.3, exercise 141.

Links

Table of n, a(n) for n=1..31.

Philip Gibbs, Judson McCranie, The Ulam Numbers up to One Trillion, (2017).

Example

87 and 97 are successive Ulam numbers and this is the first gap of 10 or larger, so 87 is in the sequence.

Crossrefs

Cf. A002858, A080288, A214603, A274522.

Sequence in context: A190062 A228231 A175657 * A280155 A075310 A075797

Adjacent sequences: A080284 A080285 A080286 * A080288 A080289 A080290

Keyword

nonn,more,hard

Author

Jud McCranie, Feb 12 2003

Extensions

Added a(23) found by Don Knuth - Jud McCranie, Aug 22 2008

a(24) on Feb 29 2012; a(25) on Jul 20 2012; and a(26) on Jul 24 2012 by Jud McCranie

a(27) found by Philip Gibbs, Sep 02 2015

a(28) found by Philip Gibbs and Jud McCranie, Sep 09 2015

a(29)-a(31) found by Philip Gibbs, Oct 2017

Missing term a(23) added by Jud McCranie, Oct 27 2017

Status

approved