A196220 Integer quotients of k^2 by the sum of the prime distinct divisors of k^2+1, where k = A196219(n).
7, 18, 121, 2268, 13520, 1377, 8550, 5157, 7381, 8496, 76176, 83521, 161604, 284229, 1028196, 4092529, 275804, 274432, 336985, 1153476, 962948, 48841, 319225, 276676, 617796, 3946827, 684450, 156349, 632025, 1256454, 6368547, 244917, 2506180, 2256004, 5410947
Offset: 1
Keywords
Examples
For k = 378, the prime distinct divisors of 378^2 + 1 are 5, 17, 41 and 378^2 /(5+17+41) = 2268. Hence 2268 is in the sequence.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..500 (calculated from the b-file at A196219)
Programs
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Maple
with(numtheory):for k from 1 to 120000 do: y:=factorset(k^2+1): s:=sum(y[i],i=1..nops(y)):if irem(k^2,s)=0 then printf(`%d, `, k^2/s):else fi:od:
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Mathematica
Select[Table[n^2/Total[Transpose[FactorInteger[n^2+1]][[1]]],{n,10^5}],IntegerQ] (* Harvey P. Dale, Apr 18 2015 *)
Comments