A171095 Triangle read by rows: row n contains sequence S_n = [s(1), ..., s(n)] where s(1) is the least semiprime pq such that the recurrence s(i+1) = sum of two prime factors of s(i) generates a chain of exactly n semiprimes.

4, 9, 6, 14, 9, 6, 33, 14, 9, 6, 62, 33, 14, 9, 6, 177, 62, 33, 14, 9, 6, 886, 445, 94, 49, 14, 9, 6, 2649, 886, 445, 94, 49, 14, 9, 6, 5294, 2649, 886, 445, 94, 49, 14, 9, 6, 68653, 5294, 2649, 886, 445, 94, 49, 14, 9, 6, 496966, 248485, 49702, 24853, 886

Offset

1,1

Links

Table of n, a(n) for n=1..60.

Example

Triangle begins:
4
9, 6
14, 9, 6
33, 14, 9, 6
62, 33, 14, 9, 6
177, 62, 33, 14, 9, 6
886, 445, 94, 49, 14, 9, 6
2649, 886, 445, 94, 49, 14, 9, 6
5294, 2649, 886, 445, 94, 49, 14, 9, 6
68653, 5294, 2649, 886, 445, 94, 49, 14, 9, 6
496966, 248485, 49702, 24853, 886, 445, 94, 49, 14, 9, 6
1490889, 496966, 248485, 49702, 24853, 886, 445, 94, 49, 14, 9, 6
16896262, 8448133, 496966, 248485, 49702, 24853, 886, 445, 94, 49, 14, 9, 6
185858761, 16896262, 8448133, 496966, 248485, 49702, 24853, 886, 445, 94, 49, 14, 9, 6
...

Crossrefs

Sequence in context: A218072 A335306 A261023 * A075065 A141553 A095065

Adjacent sequences: A171092 A171093 A171094 * A171096 A171097 A171098

Keyword

nonn,tabl

Author

N. J. A. Sloane, Sep 23 2010, based on a posting to the Sequence Fans Mailing List by Hans Havermann, Sep 10 2010

Status

approved