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A048242 Numbers that are not the sum of two abundant numbers (not necessarily distinct). 8
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 25, 26, 27, 28, 29, 31, 33, 34, 35, 37, 39, 41, 43, 45, 46, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103, 105, 107, 109 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
a(1456) = 20161 is the last term.
a(38) = 46 is the largest even term. - Alonso del Arte, Sep 11 2016
REFERENCES
Problem 13, ABACUS.
Thomas R. Parkin and Leon J. Lander, Abundant numbers, Aerospace Corporation, Los Angeles, 1964, 119 unnumbered pages. Copy deposited in UMT file.
Joe Roberts, Lure of the Integers, MAA Spectrum, 1992, p. 273, integer 20161.
David Wells, The Penguin Dictionary of Curious and Interesting Numbers, Penguin Book, 1986, p. 175, entry 20161.
LINKS
T. D. Noe, Table of n, a(n) for n = 1..1456 (complete sequence)
F. A. E. Pirani, Problems For Solution "E903", The American Mathematical Monthly, Vol. 57, No. 2, (February 1950), p. 113.
F. A. E. Pirani, Leo Moser and John Selfridge, E903, The American Mathematical Monthly, Vol. 57, No. 8. (October 1950), pp. 561-562.
Review of Abundant Numbers by Thomas R. Parkin and Leon J. Lander, Mathematics of Computation, Vol. 19, No. 90. (April 1965), p. 334.
EXAMPLE
12 is abundant, so 24=12+12 is not a term.
PROG
(PARI) setminus([1..20161], setbinop((x, y)->x+y, select(k->sigma(k, -1)>2, [1..16695]))) \\ Charles R Greathouse IV, Oct 10 2017
CROSSREFS
Complement of A048260.
Cf. A005101.
Sequence in context: A364354 A289555 A354808 * A272076 A335280 A335282
KEYWORD
fini,nonn,full
AUTHOR
Jud McCranie, Dec 11 1999
STATUS
approved

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Last modified July 23 17:14 EDT 2024. Contains 374552 sequences. (Running on oeis4.)