A087270 Solutions to gcd(x,pi(x)) = gcd(x, A000720(x)) > 1. Numbers x such that x and pi(x) have common divisor larger than one.

4, 6, 8, 10, 14, 15, 16, 20, 22, 24, 27, 30, 33, 38, 39, 40, 44, 46, 48, 50, 51, 54, 56, 58, 62, 63, 64, 66, 72, 75, 77, 78, 80, 82, 90, 92, 93, 94, 96, 100, 102, 105, 108, 114, 115, 116, 117, 118, 120, 122, 123, 124, 125, 126, 132, 134, 136, 138, 140, 142, 144, 146

Offset

1,1

Links

Table of n, a(n) for n=1..62.

Mathematica

t=Table[GCD[w, PrimePi[w]], {w, 1, 1000}]; Flatten[Position[Sign[t-1], 1]]

Crossrefs

Cf. A007053, A000720, A087266-A087269, A057809.

Sequence in context: A084808 A310660 A031020 * A316262 A075124 A067315

Adjacent sequences: A087267 A087268 A087269 * A087271 A087272 A087273

Keyword

nonn

Author

Labos Elemer, Sep 16 2003

Status

approved