OFFSET
1,1
COMMENTS
If n is odd and in this sequence, then n * 2^k is in the sequence for any k.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
4845 is in the sequence because the distinct prime divisors are {3, 5, 17, 19} and 5+17 = 3+19 = 22, where {5, 17} ==1 mod 4 and {3, 19} ==3 mod 4.
MAPLE
with(numtheory):for n from 2 to 60000 do:x:=factorset(n):n1:=nops(x):s1:=0:s3:=0:for m from 1 to n1 do: if irem(x[m], 4)=1 then s1:=s1+x[m]:else if irem(x[m], 4)=3 then s3:=s3+x[m]:else fi:fi:od:if n1>1 and s1=s3 then printf(`%d, `, n):else fi:od:
MATHEMATICA
aQ[n_] := Module[{p = FactorInteger[n][[;; , 1]]}, (t = Total[Select[p, Mod[#, 4] == 1 &]]) > 0 && t == Total[Select[p, Mod[#, 4] == 3 &]]]; Select[Range[10^5], aQ] (* Amiram Eldar, Sep 09 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Aug 28 2012
STATUS
approved