A194039 Sum of nonprime divisors of n^2 + 1.

1, 1, 11, 1, 27, 1, 86, 66, 83, 1, 123, 146, 300, 1, 227, 1, 504, 416, 363, 1, 724, 486, 912, 1, 627, 1, 1252, 786, 843, 902, 1544, 1256, 1864, 1158, 1227, 1, 2340, 1820, 1523, 1, 2582, 1766, 3490, 1938, 2027, 2118, 4499, 2306, 2403, 2502, 2603, 2706

Offset: 1

Author

Michel Lagneau, Aug 12 2011

Keywords

• nonn
• easy

Examples

			a(3) = 11 because 3^2 + 1 =  10 with the divisors {1, 2, 5, 10}, and the sum of the nonprime divisors is 1 + 10 = 11.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Programs

Mathematica

Array[ Plus @@ (Select[ Divisors[#^2+1],(!PrimeQ[#])& ])&, 75 ]

Formula

a(n) = A023890(n^2 + 1). - R. J. Mathar, Aug 14 2011