The On-Line Encyclopedia of Integer Sequences (OEIS)

A270470 revision #4

A270470

Integers n such that A001654(n) is divisible by n*(n+1)/2.

1, 3, 10, 23, 24, 47, 60, 107, 108, 167, 180, 240, 250, 323, 383, 503, 540, 575, 600, 647, 660, 683, 768, 863, 1008, 1103, 1200, 1223, 1320, 1367, 1620, 1728, 1800, 1860, 2160, 2207, 2447, 2520, 2687, 2688, 2736, 3000, 3023, 3060, 3300, 3360, 3527, 3528, 3744, 3863, 3888, 4200, 4703, 4800

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OFFSET

1,2

LINKS

Table of n, a(n) for n=1..54.

EXAMPLE

3 is a term because (1^2 + 1^2 + 2^2) / (1 + 2 + 3) = 1.

10 is a term because (1^2 + 1^2 + 2^2 + 3^2 + 5^2 + 8^2 + 13^2 + 21^2 + 34^2 + 55^2) / (1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) = 89.

PROG

(PARI) a(n) = fibonacci(n)*fibonacci(n+1);

for(n=1, 1e4, if(a(n) % (n*(n+1)/2) ==0, print1(n, ", ")));

CROSSREFS