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A222711 Numbers n such that gcd(sigma(n), phi(n)) (A009223) attains record values. 2
1, 3, 12, 14, 15, 35, 105, 190, 248, 357, 616, 812, 1045, 3080, 3135, 3339, 4064, 5049, 8323, 8636, 10659, 12441, 16065, 19780, 20026, 23374, 24871, 29029, 50065, 58435, 64285, 87685, 124355, 132957, 137885, 140335, 248501, 263055, 317205, 353133, 423657, 596037, 655707, 734517, 894387 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

RECORDS transform of A009223.

LINKS

Donovan Johnson, Table of n, a(n) for n = 1..500

N. J. A. Sloane, Transforms (The RECORDS transform returns both the high-water marks and the places where they occur).

MATHEMATICA

a[1] = 1; record = 1; a[n_] := a[n] = For[k = a[n-1] + 1, True, k++, g = GCD[DivisorSigma[1, k], EulerPhi[k]]; If[g > record, record = g; Return[k]]]; Table[a[n], {n, 1, 45}] (* Jean-Fran├žois Alcover, Oct 07 2013 *)

PROG

(PARI) mg=0; for(x=1, 1000000, g=A009223(x); if(g>mg, print1(x", "); mg=g))

CROSSREFS

Cf. A009223, A222712.

Sequence in context: A063444 A117061 A089919 * A176796 A242130 A286386

Adjacent sequences:  A222708 A222709 A222710 * A222712 A222713 A222714

KEYWORD

nonn,nice

AUTHOR

Phil Carmody, Mar 01 2013

STATUS

approved

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Last modified December 5 10:45 EST 2019. Contains 329751 sequences. (Running on oeis4.)