A073319 Numbers n such that A073318(n) = 2^phi(n) - Sum_{j=0..n} binomial(phi(n), phi(j)) is positive.

19, 23, 29, 31, 37, 43, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 121, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 289, 293

Offset

1,1

Links

Table of n, a(n) for n=1..55.

Formula

Solutions to A066781(x) - A073317(x) > 0.

Example

Several values are composites: 121, 289, 437, 529, ..., 961, 989. Primes like 2, ..., 17, 41 are not here.

Mathematica

g[x_] := EulerPhi[x] Do[s=2^g[n]-Apply[Plus, Table[Binomial[g[n], g[j]], {j, 0, n}]]; If[Sign[s]==1&&!PrimeQ[n], k=k+1; Print[{k, n, PrimeQ[n]}]], {n, 1, 1000}]

Crossrefs

Cf. A066781, A073317, A073318.

Sequence in context: A100460 A166061 A224534 * A274048 A334093 A120640

Adjacent sequences: A073316 A073317 A073318 * A073320 A073321 A073322

Keyword

nonn

Author

Labos Elemer, Jul 26 2002

Status

approved