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 A002191 Possible values for sum of divisors of n. (Formerly M2318 N0916) 37
 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 See A083531 for the gaps, i.e., first differences. - M. F. Hasler, Mar 12 2018 Sequence in context: A066650 A007609 A285703 * A108348 A085149 A239458 Adjacent sequences:  A002188 A002189 A002190 * A002192 A002193 A002194 KEYWORD nonn AUTHOR STATUS approved

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Last modified October 18 00:21 EDT 2019. Contains 328135 sequences. (Running on oeis4.)