A109896 Group the natural numbers so that every 2n-th group product is divisible by the single number in the next group. (1), (2,3,4,5), (6), (7,8,9,10,11), (12), (13,14,15,16,17,18,19),(20), (21,22,23,24,25,26,27),(28),... Sequence contains the number of terms in the 2n-th group.

4, 5, 7, 7, 7, 8, 10, 13, 9, 9, 13, 7, 7, 11, 7, 13, 13, 11, 11, 15, 11, 13, 15, 13, 15, 16, 14, 11, 11, 13, 9, 17, 17, 19, 15, 15, 13, 17, 14, 8, 15, 18, 20, 15, 17, 17, 17, 9, 19, 11, 20, 20, 13, 19, 19, 15, 15, 9, 14, 14, 17, 16, 15, 18, 13, 20, 14, 14, 14, 17, 15, 15, 15, 21, 13

Offset

1,1

Comments

a(n) = A109895(x+1)-A109895(x)-1 - Simon Nickerson (simonn(AT)maths.bham.ac.uk), Jul 15 2005

Links

Table of n, a(n) for n=1..75.

Crossrefs

Cf. A079759, A109895, A109897.

Sequence in context: A023833 A151551 A021690 * A004221 A239504 A033557

Adjacent sequences: A109893 A109894 A109895 * A109897 A109898 A109899

Keyword

nonn

Author

Amarnath Murthy, Jul 13 2005

Extensions

More terms from Simon Nickerson (simonn(AT)maths.bham.ac.uk), Jul 15 2005

Status

approved