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

Author

Jurjen N.E. Bos

Keywords

• nonn
• nice
• easy

Examples

			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).
		

Links

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

Crossrefs

Two colors gives A005728.

Cf. A048240, A048241.

Programs

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 *)

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.

Extensions

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