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A002191 Possible values for sum of divisors of n.
(Formerly M2318 N0916)
28
1, 3, 4, 6, 7, 8, 12, 13, 14, 15, 18, 20, 24, 28, 30, 31, 32, 36, 38, 39, 40, 42, 44, 48, 54, 56, 57, 60, 62, 63, 68, 72, 74, 78, 80, 84, 90, 91, 93, 96, 98, 102, 104, 108, 110, 112, 114, 120, 121, 124, 126, 127, 128, 132, 133, 138, 140, 144, 150, 152, 156 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Distinct values attained by the sigma(n) function, in ascending order.

REFERENCES

J. W. L. Glaisher, Number-Divisor Tables. British Assoc. Math. Tables, Vol. 8, Camb. Univ. Press, 1940, p. 85.

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

T. D. Noe, Table of n, a(n) for n = 1..1000

M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972, p. 840.

MAPLE

N:= 1000: # to get all entries <= N

select(`<=`, {seq(numtheory[sigma](i), i=1..N)}, N); # Robert Israel, Jun 16 2014

MATHEMATICA

lim=1000; Select[Union[DivisorSigma[1, Range[lim]]], #<=lim &] (* T. D. Noe, May 06 2010 *)

PROG

(PARI) list(lim)=select(n->n<=lim, Set(vector(lim\=1, n, sigma(n)))) \\ Charles R Greathouse IV, Nov 12 2013

CROSSREFS

Cf. A007609.

Complement of A007369. A175192(a(n)) = 1, A054973(a(n)) >= 1. - Jaroslav Krizek, Mar 01 2010

Sequence in context: A047515 A066650 A007609 * A108348 A085149 A239458

Adjacent sequences:  A002188 A002189 A002190 * A002192 A002193 A002194

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

STATUS

approved

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Last modified March 26 23:19 EDT 2017. Contains 284141 sequences.