A372946 Numbers k that divide the k-th NSW number.

1, 7, 217, 3937, 6727, 6847, 51943, 170671, 330337, 385687, 2484247, 2566537, 2904007, 3020857, 3696967, 6465577, 9405337, 12021439, 19384207

Offset

1,2

Comments

Numbers k such that k | A002315(k).

Links

Table of n, a(n) for n=1..19.

Example

7 is a term since A002315(7) = 275807 = 7 * 39401 is divisible by 7.

Mathematica

seq[kmax_] := Module[{nsw0 = 1, nsw1 = 7, nsw2, s = {1}}, Do[nsw2 = 6*nsw1 - nsw0; If[Divisible[nsw2, k], AppendTo[s, k]]; nsw0 = nsw1; nsw1 = nsw2, {k, 2, kmax}]; s]; seq[52000]

Prog

(PARI) lista(kmax) = {my(nsw0 = 1, nsw1 = 7, nsw2); print1("1, "); for(k = 2, kmax, nsw2 = 6*nsw1 - nsw0; if(!(nsw2 % k), print1(k, ", ")); nsw0 = nsw1; nsw1 = nsw2); }

Crossrefs

Cf. A002315, A330276.

Similar sequences: A014847 (Catalan), A016089 (Lucas), A023172 (Fibonacci), A051177 (partition), A232570 (tribonacci), A246692 (Pell), A266969 (Motzkin).

Sequence in context: A114939 A193224 A319538 * A290974 A145107 A231488

Adjacent sequences: A372943 A372944 A372945 * A372947 A372948 A372949

Keyword

nonn,more

Author

Amiram Eldar, May 17 2024

Status

approved