OFFSET
1,2
COMMENTS
Length of n-th row in table A245499. - Reinhard Zumkeller, Jul 25 2014
Indices of records are 1, 2, 8, 14, 52, 99, 589, 594, 595... (A277649) - Peter Kagey, Oct 24 2016
It is conjectured that 2 never appears in this sequence. a(n) = 2 if and only if A006255(n) = A072905(n). - Peter Kagey, Oct 25 2016
a(n) is three most of the time, then 5, then 6, then 4 for the first 1000 and the first 10000 terms. At n = 72, 78 and 85, a(n) is 4 or 5 and 4 and 5 occured equally often so far. At 299, 301, 312, 322 and 403, a(n) is 4 or 6 and 4 and 6 occured equally often so far. This doesn't happen for the first 10000 terms for 5 and 6. - David A. Corneth, Oct 25 2016
REFERENCES
R. L. Graham, D. E. Knuth and O. Patashnik, Concrete Mathematics. Addison-Wesley, Reading, MA, 1990, p. 147.
LINKS
David A. Corneth, Table of n, a(n) for n = 1..10000 (first 1000 terms from Reinhard Zumkeller and Peter Kagey)
R. L. Graham, Bijection between integers and composites, Problem 1242, Math. Mag., 60 (1987), p. 180.
EXAMPLE
a(2) = 3 because the best such sequence is 2,3,6 which has three terms.
PROG
(Haskell)
a066400 = length . a245499_row -- Reinhard Zumkeller, Jul 25 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Dec 25 2001
EXTENSIONS
More terms from John W. Layman, Jul 14 2003
More terms from Joshua Zucker, May 18 2006
STATUS
approved