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

1,2

Comments

Numbers k such that k | A000930(k).

Links

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

Example

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.

Mathematica

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

Prog

(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); }

Crossrefs

Cf. A000930.

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

Sequence in context: A018809 A226882 A214903 * A256584 A117866 A365691

Adjacent sequences: A372897 A372898 A372899 * A372901 A372902 A372903

Keyword

nonn

Author

Amiram Eldar, May 16 2024

Status

approved