A125499 Deficient even numbers.

2, 4, 8, 10, 14, 16, 22, 26, 32, 34, 38, 44, 46, 50, 52, 58, 62, 64, 68, 74, 76, 82, 86, 92, 94, 98, 106, 110, 116, 118, 122, 124, 128, 130, 134, 136, 142, 146, 148, 152, 154, 158, 164, 166, 170, 172, 178, 182, 184, 188, 190, 194, 202, 206, 212, 214, 218, 226, 230

Offset: 1

Author

Tanya Khovanova, Dec 27 2006

Keywords

• nonn

Examples

			22 is in the sequence because it is even and its sum of divisors 1+2+11+22=36 is less than 2*22.
		

Links

• R. J. Mathar, Table of n, a(n) for n = 1..3375

Crossrefs

Cf. A005100 = deficient numbers.

Programs

Maple

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
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

Mathematica

Select[Range[2,250,2],DivisorSigma[1,#]<2#&] (* Harvey P. Dale, Apr 04 2023 *)

Extensions

More terms from Emeric Deutsch, Jan 01 2007