A285122 Min(|d(k+1-i) - d(i)|, for i = 1..k), where d(1),..,d(k) are the divisors of n^2+1.

1, 4, 3, 16, 11, 36, 5, 8, 39, 100, 59, 24, 7, 196, 111, 256, 19, 12, 179, 400, 9, 92, 43, 576, 311, 676, 63, 152, 419, 36, 11, 16, 99, 76, 611, 1296, 127, 68, 759, 1600, 29, 348, 13, 136, 1011, 44, 31, 456, 1199, 20, 1299, 536, 271, 2916, 55, 3136, 15, 668

Offset

1,2

Links

Clark Kimberling, Table of n, a(n) for n = 1..10000

Formula

a(n)=A056737(A002522(n)).

Example

5^2 + 1 = 26 has divisors 1,2,13,26, so that k=4 and d(k+1-i) - d(i) ranges through {-25,-11,11,25}, so that a(5) = 11.

Mathematica

f[n_] := f[n] = n^2+1; Table[Divisors[f[n]] - Reverse[Divisors[f[n]]], {n, 1, 10}]
Table[Min[Abs[Divisors[f[n]] - Reverse[Divisors[f[n]]]]], {n, 1, 100}]

Crossrefs

Cf. A002522, A002378, A056737.

Sequence in context: A269512 A270128 A084471 * A277773 A277800 A278469

Adjacent sequences: A285119 A285120 A285121 * A285123 A285124 A285125

Keyword

nonn,easy

Author

Clark Kimberling, Apr 11 2017

Status

approved