A048134 Number of colors that can be mixed with up to n units of yellow, blue, red.

0, 3, 6, 13, 22, 40, 55, 88, 118, 163, 205, 280, 334, 436, 517, 625, 733, 901, 1018, 1225, 1381, 1591, 1786, 2083, 2287, 2617, 2887, 3238, 3544, 4006, 4306, 4831, 5239, 5749, 6205, 6817, 7267, 8005, 8572, 9280, 9880, 10780, 11374, 12361

Offset

0,2

Links

T. D. Noe, Table of n, a(n) for n = 0..1000

Formula

a(n) = number of triples (i, j, k) with 1 <= i+j+k <= n and gcd(i, j, k) = 1.

Cumulative sums of A048240(k) for k>0.

Example

a(2)=6: primary and secondary colors (Y^1, B^1, R^1, Y^1*B^1, Y^1*R^1, B^1*R^1).

Mathematica

Accumulate[ Table[ Sum[ MoebiusMu[n/d]*(d + 1)*(d + 2)/2, {d, Divisors[n]}], {n, 0, 43}]] (* Jean-François Alcover, Jul 16 2012, after Vladeta Jovovic *)

Crossrefs

Two colors gives A005728.

Cf. A048240, A048241.

Sequence in context: A361276 A211870 A239987 * A058397 A174369 A308747

Adjacent sequences: A048131 A048132 A048133 * A048135 A048136 A048137

Keyword

nonn,nice,easy

Author

Jurjen N.E. Bos

Extensions

More terms from Robin Trew (trew(AT)hcs.harvard.edu).

Status

approved