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A053868 Numbers whose sum of proper divisors is odd. 7
2, 3, 4, 5, 7, 8, 11, 13, 15, 16, 17, 18, 19, 21, 23, 27, 29, 31, 32, 33, 35, 36, 37, 39, 41, 43, 45, 47, 50, 51, 53, 55, 57, 59, 61, 63, 64, 65, 67, 69, 71, 72, 73, 75, 77, 79, 83, 85, 87, 89, 91, 93, 95, 97, 98, 99, 100, 101, 103, 105, 107, 109, 111, 113, 115, 117, 119 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Numbers which are twice squares, even squares or odd nonsquares.
LINKS
PROG
(Haskell)
a053868 n = a053868_list !! (n-1)
a053868_list = filter (odd . a001065) [1..]
-- Reinhard Zumkeller, Nov 01 2015, Sep 15 2011
CROSSREFS
Sequence in context: A058586 A090467 A177202 * A241912 A269870 A307824
KEYWORD
nonn
AUTHOR
Henry Bottomley, Mar 29 2000
EXTENSIONS
Improved name from Omar E. Pol, Aug 14 2009
STATUS
approved

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Last modified July 17 16:16 EDT 2024. Contains 374377 sequences. (Running on oeis4.)