A055201 Numbers k such that A005728(k) is prime.

1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 15, 17, 18, 22, 23, 24, 29, 36, 37, 40, 53, 55, 59, 60, 61, 62, 63, 68, 69, 74, 83, 86, 93, 97, 107, 109, 115, 116, 117, 118, 123, 128, 129, 139, 142, 147, 153, 154, 157, 158, 162, 167, 170, 175, 179, 181, 182, 183, 193, 194, 196

Offset

1,2

Comments

From a question by Leo Moser.

References

Martin Gardner, "The Last Recreations," Chapter entitled "Strong Laws of Small Primes," Copernicus, Springer-Verlag, NY, 1997, page 199.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Leo Moser, Problem P42, Canadian Mathematical Bulletin, Vol. 5, No. 3 (1962), pp. 312-313.

Mathematica

s=1; Do[s = s + EulerPhi[n]; If[PrimeQ[s], Print[n]], {n, 200}]

Crossrefs

Cf. A005728.

Complement of A055197.

Sequence in context: A002244 A037173 A091897 * A213006 A068998 A072303

Adjacent sequences: A055198 A055199 A055200 * A055202 A055203 A055204

Keyword

easy,nonn

Author

Robert G. Wilson v, Jul 04 2000

Status

approved