A174535 Odd almost practical numbers.

945, 1575, 2205, 2835, 3465, 4095, 4725, 5355, 5775, 5985, 6615, 6825, 7245, 7875, 8085, 8505, 9135, 9555, 9765, 10395, 11025, 11655, 12285, 12705, 12915, 13545, 14175, 14805, 15015, 15435, 16065, 16695, 17325, 17955, 18585, 19215, 19635

Offset

1,1

Comments

This is Stewart's set O*. Note that 15 divides all such numbers. This sequence appears to be a subsequence of the odd abundant numbers, A005231. See A174533 for additional comments.

105 | a(n) for all n. - David A. Corneth, Sep 12 2025

Links

David A. Corneth, Table of n, a(n) for n = 1..10000 (first 4000 terms from Amiram Eldar)

B. M. Stewart, Sums of distinct divisors, American Journal of Mathematics, Vol. 76, No. 4 (1954), pp. 779-785.

Example

945 is in the sequence because 945 is odd and all but two positive integers <= sigma(945) = 1920 are the sum of some distinct divisors of 945. The two numbers <= sigma(945) = 1920 that are not the sum of some distinct divisors of 945 are 2 and 1920-2 = 1918. - David A. Corneth, Sep 12 2025

Crossrefs

Cf. A005231, A174533, A174534.

Sequence in context: A381550 A005231 A174865 * A243104 A381547 A006038

Adjacent sequences: A174532 A174533 A174534 * A174536 A174537 A174538

Keyword

nonn

Author

T. D. Noe, Mar 21 2010

Status

approved