OFFSET
1,1
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..100
EXAMPLE
948 is in the sequence because the prime distinct divisors of 948^2 + 1 are {5, 17, 97, 109} and 5+109 = 17+97 = 114, where {17, 97} == 1 mod 8 and {5, 109} == 5 mod 8.
MAPLE
with(numtheory):for n from 1 to 10^6 do:x:=factorset(n^2+1):n1:=nops(x): s1:=0:s3:=0:for m from 1 to n1 do: if irem(x[m], 8)=1 then s1:=s1+x[m]: else if irem(x[m], 8)=5 then s3:=s3+x[m]:else fi:fi:od:if n1>1 and s1=s3 then printf(`%d, `, n):else fi:od:
MATHEMATICA
dpdQ[n_]:=Module[{pd=Transpose[FactorInteger[n^2+1]][[1]]}, Total[ Select[ pd, Mod[ #, 8] ==1&]]==Total[Select[pd, Mod[#, 8]==5&]]]; Select[Range[ 2, 9*10^6], dpdQ] (* Harvey P. Dale, Jul 02 2016 *)
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
Michel Lagneau, Aug 28 2012
STATUS
approved