

A080287


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


4



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
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OFFSET

1,2


COMMENTS



REFERENCES

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


LINKS



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



KEYWORD

nonn,more,hard


AUTHOR



EXTENSIONS

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(29)a(31) found by Philip Gibbs, Oct 2017
Missing term a(23) added by Jud McCranie, Oct 27 2017


STATUS

approved



