OFFSET
1,1
COMMENTS
Subsequence of A063990.
EXAMPLE
Deficient aliquot parts of 1184 are 1,2,4,8,16,32,37,74,148,296,592 and their sum is 1210.
Deficient aliquot parts of 1210 are 1,2,5,10,11,22,55,110,121,242,605 and their sum is 1184.
MAPLE
with(numtheory): P:=proc(q) local a, b, c, d, k, n; for n from 1 to q do
a:=sort([op(divisors(n))]); b:=0; for k from 1 to nops(a)-1 do if 2*a[k]>sigma(a[k]) then b:=b+a[k]; fi; od;
c:=sort([op(divisors(b))]); d:=0; for k from 1 to nops(c)-1 do if 2*c[k]>igma(c[k]) then d:=d+c[k]; fi; od; if d=n and d<>b then print(n); fi; od; end: P(10^6);
MATHEMATICA
defQ[n_] := DivisorSigma[1, n] < 2n; s[n_] := DivisorSum[n, #&, #<n && defQ[#]&]; seq={}; Do[m=s[n]; If[m>n && s[m]==n, AppendTo[seq, {n, m}]], {n, 1, 10^5}]; Flatten[seq] (* Amiram Eldar, Jan 26 2019 *)
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
Paolo P. Lava, Jan 04 2017
EXTENSIONS
More terms from Amiram Eldar, Jan 26 2019
STATUS
approved