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%I #12 Apr 04 2023 11:53:14
%S 2,4,8,10,14,16,22,26,32,34,38,44,46,50,52,58,62,64,68,74,76,82,86,92,
%T 94,98,106,110,116,118,122,124,128,130,134,136,142,146,148,152,154,
%U 158,164,166,170,172,178,182,184,188,190,194,202,206,212,214,218,226,230
%N Deficient even numbers.
%H R. J. Mathar, <a href="/A125499/b125499.txt">Table of n, a(n) for n = 1..3375</a>
%e 22 is in the sequence because it is even and its sum of divisors 1+2+11+22=36 is less than 2*22.
%p with(numtheory): a:=proc(n) if sigma(n)<2*n and n mod 2 = 0 then n else fi end: seq(a(n),n=1..290); # _Emeric Deutsch_, Jan 01 2007
%p isA005100 := proc(n) if numtheory[sigma](n) < 2*n then RETURN(true) ; else RETURN(false) ; fi ; end : for n from 2 to 800 by 2 do if isA005100(n) then printf("%d,",n) ; fi ; od ; # _R. J. Mathar_, Jan 07 2007
%t Select[Range[2,250,2],DivisorSigma[1,#]<2#&] (* _Harvey P. Dale_, Apr 04 2023 *)
%Y Cf. A005100 = deficient numbers.
%K nonn
%O 1,1
%A _Tanya Khovanova_, Dec 27 2006
%E More terms from _Emeric Deutsch_, Jan 01 2007
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