A372900 Numbers k that divide the k-th term of Narayana's cows sequence.

1, 6, 12, 52, 390, 650, 663, 2077, 11479, 31671, 41158, 43508, 104894, 123682, 127370, 170819, 175075, 191516, 266247, 274378, 327159, 341638, 366903, 383847, 733985, 1236087, 1755063, 1763775, 2277964, 2364654, 3165126, 6726156, 7007823, 7221084, 10903815

Offset: 1

Author

Amiram Eldar, May 16 2024

Keywords

• nonn

Comments

Numbers k such that k | A000930(k).

Examples

			6 is a term since A000930(6) = 6 is divisible by 6.
12 is a term since A000930(12) = 60 = 5 * 12 is divisible by 12.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..43

Crossrefs

Cf. A000930.

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

Programs

Mathematica

With[{m = 50000}, Position[LinearRecurrence[{1, 0, 1}, {1, 1, 2}, m]/Range[m], _?IntegerQ] // Flatten]

PARI

lista(kmax) = {my(nc1 = 1, nc2 = 1, nc3 = 2, nc4); print1("1, "); for(k = 4, kmax, nc4 = nc1 + nc3; if(!(nc4 % k), print1(k, ", ")); nc1 = nc2; nc2 = nc3; nc3 = nc4);}