A125286 a(0)=1. a(n) = a(n-1) + (the largest term among {a(0),a(1),...a(n-1)} that has the same number of positive divisors as n).

1, 2, 4, 6, 10, 12, 22, 24, 46, 50, 96, 98, 196, 198, 244, 290

Offset

0,2

Comments

a(16) does not exist because no earlier term has exactly 5 divisors. However, arbitrary modifications of the sequence's definition (such as letting a(n) = a(n-1) + 0 if no earlier term has the same number of divisors as n, or letting a(n) = a(n-1) + the largest earlier term with at most n divisors, etc.) would allow the sequence to be infinite in length.

Links

Table of n, a(n) for n=0..15.

Example

9 has 3 divisors. So a(9) = a(8) + the largest earlier term with 3 divisors. a(3) = 4 is the only earlier term with 3 divisors, so a(9) = a(8) + 4 = 50.

Crossrefs

Sequence in context: A133871 A068514 A074645 * A045963 A128169 A095923

Adjacent sequences: A125283 A125284 A125285 * A125287 A125288 A125289

Keyword

fini,full,nonn

Author

Leroy Quet, Jan 26 2007

Status

approved