A191914 Smallest number m greater than n such that the happy couples of m and n have a member in common.

2, 3, 5, 6, 7, 8, 10, 12, 12, 11, 13, 15, 17, 18, 20, 20, 19, 22, 23, 24, 28, 32, 26, 28, 30, 27, 29, 35, 31, 35, 37, 34, 39, 38, 42, 42, 41, 40, 52, 46, 43, 48, 47, 52, 55, 54, 50, 56, 56, 51, 53, 60, 58, 62, 70, 63, 69, 59, 61, 68, 65, 66, 72, 72, 67, 86

Offset

1,1

Comments

The intersection of {A007966(n),A007967(n)} and {A007966(a(n)),A007967(a(n))} is not empty, but the intersection of {A007966(n),A007967(n)} and {A007966(m),A007967(m)} is empty for n<m<a(n).

Links

Table of n, a(n) for n=1..66.

J. H. Conway, On Happy Factorizations, J. Integer Sequences, Vol. 1, 1998, #1.

Example

Let hc(n) = (A007966(n),A007967(n)),
n=6, a(6) =  8: hc(6) = (2,3) and hc(8)  = (2,4)  with common 2,
n=7, a(7) = 10: hc(7) = (7,1) and hc(10) = (1,10) with common 1,
n=8, a(8) = 12: hc(8) = (2,4) and hc(12) = (3,4)  with common 4,
n=9, a(9) = 12: hc(9) = (3,3) and hc(12) = (3,4)  with common 3.

Crossrefs

Sequence in context: A181807 A059870 A179813 * A329898 A145353 A013936

Adjacent sequences: A191911 A191912 A191913 * A191915 A191916 A191917

Keyword

nonn

Author

Reinhard Zumkeller, Jun 19 2011

Status

approved