A248516 n^2+1 divided by its largest prime factor.

1, 1, 2, 1, 2, 1, 10, 5, 2, 1, 2, 5, 10, 1, 2, 1, 10, 25, 2, 1, 26, 5, 10, 1, 2, 1, 10, 5, 2, 17, 26, 25, 10, 13, 2, 1, 10, 85, 2, 1, 58, 5, 50, 13, 2, 29, 130, 5, 2, 41, 2, 5, 10, 1, 34, 1, 250, 5, 2, 13, 2, 5, 10, 17, 2, 1, 10, 125, 2, 169, 2, 85, 130, 1, 58

Offset

1,3

Comments

a(n)=1 iff n^2+1 is prime (see A002496).

Conjecture: The Fibonacci numbers in the sequence are 1, 2, 5, 13, 34, 89, 233, 377, 610, 1597, 4181, 10946, 28657, 75025, 121393, 196418, ... including all of A001519.

Links

Michel Lagneau, Table of n, a(n) for n = 1..10000

Formula

a(n) = A002522(n)/A014442(n).

a(n) = A052126(1+n^2). - R. J. Mathar, Jun 18 2015

Maple

A248516 := proc(n)
    n^2+1 ;
    %/A006530(%) ;
end proc:
seq(A248516(n), n=1..20) ; # R. J. Mathar, Jun 18 2015

Mathematica

Table[(n^2 + 1)/FactorInteger[n^2 + 1][[-1, 1]], {n, 75}] (* Michael De Vlieger, Jun 19 2015 *)

Prog

(PARI) a(n) = my(x=n^2+1); my(f=factor(x)); x/f[#f~, 1]; \\ Michel Marcus, Jun 18 2015

Crossrefs

Cf. A001519, A002522, A014442, A245236.

Sequence in context: A110179 A071559 A071560 * A097749 A126906 A179508

Adjacent sequences: A248513 A248514 A248515 * A248517 A248518 A248519

Keyword

nonn,easy

Author

Michel Lagneau, Jun 18 2015

Status

approved