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A094472 a[n]=n.tau[n]-sigma[n]-phi[n]=n.A000005[n]-A000203[n]-A000010[n]. 0
-1, 0, 0, 3, 0, 10, 0, 13, 8, 18, 0, 40, 0, 26, 28, 41, 0, 63, 0, 70, 40, 42, 0, 124, 24, 50, 50, 100, 0, 160, 0, 113, 64, 66, 68, 221, 0, 74, 76, 214, 0, 228, 0, 160, 168, 90, 0, 340, 48, 187, 100, 190, 0, 294, 108, 304, 112, 114, 0, 536, 0, 122, 238, 289, 128, 364, 0, 250, 136, 392, 0, 645, 0, 146, 286, 280, 152, 432, 0, 582 (list; graph; refs; listen; history; internal format)
OFFSET

1,4

EXAMPLE

If n is prime, then a[n]=0.

Is the reverse statement true [namely (a[n]=0 -> n=prime)]?

MATHEMATICA

Table[w*DivisorSigma[0, w]-DivisorSigma[1, w]-EulerPhi[w], {w, 1, 100}]

CROSSREFS

Cf. A000005, A000010, A000203, A094471.

Sequence in context: A118534 A187427 A167352 * A028850 A138364 A095364

Adjacent sequences:  A094469 A094470 A094471 * A094473 A094474 A094475

KEYWORD

sign

AUTHOR

Labos E. (labos(AT)ana.sote.hu), May 28 2004

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Last modified February 15 03:33 EST 2012. Contains 205694 sequences.