A094702 Least linear combinations of phi(n) and sigma(n) are multiple.

2, 12, 42, 90, 110, 152, 171, 208, 231, 336, 408, 476, 506, 765, 783, 840, 1242, 1380, 1584, 1911, 2120, 2162, 2528, 2604, 2688, 2706, 2720, 2970, 3162, 3172, 3325, 3392, 3422, 3619, 3654, 3708, 3870, 4144, 4371, 4472, 4508, 4712, 4760, 4876, 5256, 5372

Offset: 0

Author

Walter Nissen, May 20 2004

Keywords

• nonn

Comments

"Multiple" is used here with two distinct meanings. The linear combination of phi and sigma must be a multiple of the argument to be tallied (Cf. A094701). There must be a multiple, i.e. at least 2, of those linear combinations for the value to be in this sequence. 3 is not in this sequence because there is only one linear combination with minimal sum, 2, viz., 1*phi(3) + 1*sigma(3), which is a multiple of 3.

Examples

			2 is in the sequence because there are 3 minimal combinations of phi(2) and sigma(2), viz., 2*sigma(2), 1*phi(2) + 1*sigma(2) and 2*phi(2), all of which are multiples of 2 and all of which have coefficients totaling 2, viz., 0+2 = 1+1 = 2+0.
		

Crossrefs

Cf. A000010, A000203, A094701.