A060398 Values of k associated with A060397.

1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 2, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 2, 1, 0, 0, 1, 0, 2, 1, 0, 0, 1, 0, 1, 1, 0, 2, 1, 0, 0, 1, 0, 4, 1, 0, 3, 1, 0, 1, 1, 0, 2, 1, 0, 0, 1, 0, 1, 1, 0, 2, 1, 0, 1, 1, 0, 2, 1, 0, 0, 1, 0, 0, 1, 0, 4, 1, 0, 1, 1, 0, 2, 1, 0, 0, 1, 0, 3, 1, 0, 2, 1, 0, 1, 1, 0, 2

Offset: 0

Author

N. J. A. Sloane, Apr 04 2001

Keywords

• nonn
• easy

Links

• T. D. Noe, Table of n, a(n) for n = 0..10000
• Carlos Rivera, Conjecture 17. The Ludovicus conjecture about the Euler trinomials, The Prime Puzzles & Problems Connection.

Crossrefs

Cf. A060397.

Programs

Mathematica

a[n_] := Switch[n, 0, 1, , Module[{f, kmax0 = 2}, f[kmax] := f[kmax] = MinimalBy[Table[{k, FactorInteger[k^2 + k + 2 n + 1][[1, 1]]}, {k, 0, kmax}], Last, 1]; f[kmax = kmax0]; f[kmax = 2 kmax]; While[f[kmax] != f[kmax/2], kmax = 2 kmax]; f[kmax][[1, 1]]]];
Table[a[n], {n, 0, 105}] (* Jean-François Alcover, Aug 15 2022 *)

Extensions

More terms from T. D. Noe, Mar 12 2007