A071349 Numbers k for which the GCD of the k-th primorial number and its totient (A058250) sets record.

1, 2, 4, 5, 9, 10, 15, 16, 17, 23, 27, 28, 35, 39, 40, 41, 43, 49, 56, 57, 61, 62, 64, 66, 69, 72, 73, 76, 77, 91, 92, 96, 97, 102, 103, 104, 107, 111, 114, 117, 119, 127, 128, 137, 139, 143, 146, 150, 154, 155, 166, 171, 181, 182, 186, 195, 196, 201, 208, 214, 215

Offset

1,2

Links

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

Formula

If A058250(m) > A058250(k) for all k < m then m is a term.

Mathematica

q[n_] := Product[Prime[i], {i, 1, n}]; fq[n_] := Product[Prime[i] - 1, {i, 1, n}];
a=0; Do[s=GCD[q[n], fq[n]]; If[s>a, a=s; Print[n]], {n, 1, 1000}]

Crossrefs

Cf. A058250, A002110, A000010, A005867, A071350.

Sequence in context: A091271 A063985 A050052 * A282737 A039891 A280729

Adjacent sequences: A071346 A071347 A071348 * A071350 A071351 A071352

Keyword

nonn

Author

Labos Elemer, May 21 2002

Status

approved