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A048242 Numbers that are not the sum of two abundant numbers (not necessarily distinct).

%I A048242 #37 Jul 20 2023 07:20:11
%S A048242 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,
%T A048242 28,29,31,33,34,35,37,39,41,43,45,46,47,49,51,53,55,57,59,61,63,65,67,
%U A048242 69,71,73,75,77,79,81,83,85,87,89,91,93,95,97,99,101,103,105,107,109
%N A048242 Numbers that are not the sum of two abundant numbers (not necessarily distinct).
%C A048242 a(1456) = 20161 is the last term.
%C A048242 a(38) = 46 is the largest even term. - _Alonso del Arte_, Sep 11 2016
%D A048242 Problem 13, ABACUS.
%D A048242 Thomas R. Parkin and Leon J. Lander, Abundant numbers, Aerospace Corporation, Los Angeles, 1964, 119 unnumbered pages. Copy deposited in UMT file.
%D A048242 Joe Roberts, Lure of the Integers, MAA Spectrum, 1992, p. 273, integer 20161.
%D A048242 David Wells, The Penguin Dictionary of Curious and Interesting Numbers, Penguin Book, 1986, p. 175, entry 20161.
%H A048242 T. D. Noe, <a href="/A048242/b048242.txt">Table of n, a(n) for n = 1..1456</a> (complete sequence)
%H A048242 F. A. E. Pirani, <a href="http://www.jstor.org/stable/2304999">Problems For Solution "E903"</a>, The American Mathematical Monthly, Vol. 57, No. 2, (February 1950), p. 113.
%H A048242 F. A. E. Pirani, Leo Moser and John Selfridge, <a href="http://www.jstor.org/stable/2307953">E903</a>, The American Mathematical Monthly, Vol. 57, No. 8. (October 1950), pp. 561-562.
%H A048242 Project Euler, <a href="https://projecteuler.net/problem=23">Non-abundant sums Problem 23</a>
%H A048242 Review of <a href="http://dx.doi.org/10.1090/S0025-5718-65-99950-3">Abundant Numbers by Thomas R. Parkin and Leon J. Lander</a>, Mathematics of Computation, Vol. 19, No. 90. (April 1965), p. 334.
%e A048242 12 is abundant, so 24=12+12 is not a term.
%o A048242 (PARI) setminus([1..20161], setbinop((x,y)->x+y, select(k->sigma(k,-1)>2,[1..16695]))) \\ _Charles R Greathouse IV_, Oct 10 2017
%Y A048242 Complement of A048260.
%Y A048242 Cf. A005101.
%K A048242 fini,nonn,full
%O A048242 1,2
%A A048242 _Jud McCranie_, Dec 11 1999