A090499 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give

A090499

Group the natural numbers so that the sum of the numbers of divisors of the members of the (n+1)th group exceeds that for the n-th group. Sequence contains the first term of each group.

1, 2, 3, 5, 7, 10, 13, 17, 21, 25, 30, 34, 39, 44, 49, 55, 61, 69, 77, 85, 94, 103, 113, 124, 134, 145, 157, 170, 183, 197, 211, 227, 242, 257, 273, 289, 307, 325, 344, 362, 381, 401, 421, 443, 465, 487, 511, 535, 560, 583, 607, 631, 659, 685, 713, 740, 767, 793

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..58.

EXAMPLE

The groups are {1}, {2}, {3, 4}, {5, 6}, {7, 8, 9}, ... The 4th group has total d(5)+d(6) = 6. d(7)+d(8) is also 6, so 9 must be included in the 5th group to make a larger total.

CROSSREFS

Cf. A090500, A090501.

Sequence in context: A029707 A175092 A265250 * A229170 A022335 A022780

Adjacent sequences: A090496 A090497 A090498 * A090500 A090501 A090502

KEYWORD

nonn

AUTHOR

Amarnath Murthy, Dec 04 2003

EXTENSIONS

More terms from David Wasserman, Dec 08 2005

STATUS

approved