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A134322 Positive integers with fewer non-isolated divisors than isolated divisors. A divisor, k, of n is non-isolated if (k-1) or (k+1) also divides n. A divisor, k, of n is isolated if neither (k-1) nor (k+1) divides n. +0
3
1, 3, 5, 7, 9, 11, 13, 15, 16, 17, 19, 21, 23, 25, 27, 28, 29, 31, 32, 33, 35, 36, 37, 39, 41, 43, 44, 45, 47, 48, 49, 50, 51, 52, 53, 54, 55, 57, 59, 61, 63, 64, 65, 66, 67, 68, 69, 70, 71, 73, 75, 76, 77, 78, 79, 80, 81, 83, 85, 87, 88, 89, 91, 92, 93, 95, 96, 97, 98, 99, 100 (list; graph; listen)
OFFSET

1,2

COMMENT

All odd positive integers are in the sequence, since every divisor of any odd number is isolated.

LINKS

Leroy Quet, Home Page (listed in lieu of email address)

EXAMPLE

The divisors of 50 are 1,2,5,10,25,50. Of these, 1 and 2 are non-isolated divisors and 5,10,25,50 are isolated divisors. There are fewer non-isolated divisors (2 in number) than isolated divisors (4 in number), so 50 is in the sequence.

CROSSREFS

Cf. A134320, A134321.

Sequence in context: A064996 A091569 A120890 this_sequence A063460 A024806 A084834

Adjacent sequences: A134319 A134320 A134321 this_sequence A134323 A134324 A134325

KEYWORD

nonn

AUTHOR

Leroy Quet Oct 20 2007

EXTENSIONS

Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Jun 24 2008

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Last modified December 4 08:07 EST 2009. Contains 170310 sequences.


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