

A053869


Sum of divisors of n less than n is even.


6



1, 6, 9, 10, 12, 14, 20, 22, 24, 25, 26, 28, 30, 34, 38, 40, 42, 44, 46, 48, 49, 52, 54, 56, 58, 60, 62, 66, 68, 70, 74, 76, 78, 80, 81, 82, 84, 86, 88, 90, 92, 94, 96, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 121, 122, 124, 126, 130, 132, 134, 136, 138, 140
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OFFSET

1,2


COMMENTS

Numbers which if odd are squares and which if even are neither squares nor twice squares.
Numbers whose sum of proper divisors is even.  Omar E. Pol, Aug 14 2009


LINKS



FORMULA



PROG

(Haskell)
a053869 n = a053869_list !! (n1)
a053869_list = filter (even . a001065) [1..]
a053869_list = map (+ 1) $ findIndices even $ map a001065 [1..]


CROSSREFS



KEYWORD

nonn,easy


AUTHOR



EXTENSIONS



STATUS

approved



