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A071349 Numbers k for which the GCD of the k-th primorial number and its totient (A058250) sets record. 3
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified July 14 18:26 EDT 2020. Contains 335729 sequences. (Running on oeis4.)