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

1,1

Links

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

Example

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

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 *)

Crossrefs

Cf. A005100 = deficient numbers.

Sequence in context: A360912 A226872 A132895 * A240092 A153974 A290476

Adjacent sequences: A125496 A125497 A125498 * A125500 A125501 A125502

Keyword

nonn

Author

Tanya Khovanova, Dec 27 2006

Extensions

More terms from Emeric Deutsch, Jan 01 2007

Status

approved