A070296 - OEIS

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A070296

Let sphi(k) = number of primes less than k and coprime to it (A048865); then a(n) = number of integers m with sphi(m) = n.

2, 3, 2, 4, 3, 3, 4, 5, 3, 5, 6, 1, 4, 5, 8, 2, 5, 4, 3, 5, 4, 7, 7, 5, 2, 3, 3, 6, 10, 5, 7, 2, 10, 3, 4, 7, 5, 4, 7, 4, 7, 3, 5, 2, 12, 10, 5, 3, 4, 5, 2, 10, 6, 7, 5, 3, 5, 4, 4, 9, 14, 3, 3, 5, 12, 8, 7, 3, 5, 7, 6, 7, 5, 5, 6, 7, 6, 9, 7, 4, 7, 5, 5, 3, 8, 7, 3, 2, 7, 10, 7, 7, 4, 7, 7

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,1

LINKS

Table of n, a(n) for n=0..94.

FORMULA

a(n) = number of m such that A048865(m) = n.

EXAMPLE

a(4) = 3. The three values of m for which sphi(m) = 4 are 11, 14 and 15. The coprime primes less than 11 are 2, 3, 5 and 7. The coprime primes less than 14 are 3, 5, 11 and 13. The coprime primes less than 15 are 2, 7, 11 and 13.

MATHEMATICA

(continuing from A048865) Table[Count[t, i], {i, 0, 150}]

CROSSREFS

Sequence in context: A318046 A246348 A205782 * A303581 A216647 A072645

Adjacent sequences: A070293 A070294 A070295 * A070297 A070298 A070299

KEYWORD

nonn

AUTHOR

Amarnath Murthy, May 10 2002

EXTENSIONS

More terms from Hans Havermann, Jun 04, 2002

STATUS

approved