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A204824 Abundant numbers with odd sum of divisors. 4
18, 36, 72, 100, 144, 162, 196, 200, 288, 324, 392, 400, 450, 576, 648, 784, 800, 882, 900, 968, 1152, 1296, 1352, 1458, 1568, 1600, 1764, 1800, 1936, 2178, 2304, 2450, 2500, 2592, 2704, 2916, 3042, 3136, 3200, 3528, 3600, 3872, 4050, 4356, 4608, 4624, 4900, 5000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers m from A005101 such that sigma(m) = A000203(m) is odd.

Complement of A204825 with respect to A005101 (abundant numbers).

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Eric Weisstein's World of Mathematics, Abundant Number

EXAMPLE

Abundant number 18 is in sequence because sigma(18) = 39 (odd number).

PROG

(PARI) list(lim)=my(v=List(), t); for(n=1, sqrtint(lim\1), if(sigma(t=n^2, -1)>2, listput(v, t))); for(n=1, sqrtint(lim\2), if(sigma(t=2*n^2, -1)>2, listput(v, t))); Set(v) \\ Charles R Greathouse IV, Feb 21 2017

CROSSREFS

Cf. A204825 (abundant numbers with even sum of divisors), A204826 (deficient numbers with odd sum of divisors), A204827 (deficient numbers with even sum of divisors).

Sequence in context: A070224 A083211 A156903 * A252424 A115550 A061713

Adjacent sequences:  A204821 A204822 A204823 * A204825 A204826 A204827

KEYWORD

nonn

AUTHOR

Jaroslav Krizek, Jan 22 2012

EXTENSIONS

a(42) inserted by Charles R Greathouse IV, Feb 21 2017

STATUS

approved

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Last modified May 20 03:05 EDT 2019. Contains 323412 sequences. (Running on oeis4.)