A065392 a(n) = A062401(A065391(n)): phi(sigma(m)) peak values for numbers m (listed in A065391) at which those peaks are first reached.

1, 2, 6, 8, 12, 30, 36, 72, 126, 180, 360, 432, 660, 930, 1512, 2160, 3300, 3780, 5184, 6552, 11160, 13860, 19800, 23232, 32760, 45360, 47520, 50400, 58080, 61776, 102300, 110160, 137592, 155520, 163296, 196560, 212960, 252000, 272160, 284580

Offset

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..249 (terms 1..100 from Harry J. Smith)

Mathematica

With[{s = Array[EulerPhi@ DivisorSigma[1, #] &, 10^5]}, Union@ FoldList[Max, s] ] (* Michael De Vlieger, Dec 06 2018 *)

Prog

(PARI) { n=r=0; for (m=1, 10^9, x=eulerphi(sigma(m)); if (x > r, r=x; write("b065392.txt", n++, " ", x); if (n==100, return)) ) } \\ Harry J. Smith, Oct 18 2009

Crossrefs

Cf. A000010, A000203, A062401, A065389, A065390, A065391, A065393, A065394.

Sequence in context: A226818 A113462 A388280 * A030457 A296300 A358970

Adjacent sequences: A065389 A065390 A065391 * A065393 A065394 A065395

Keyword

nonn

Author

Labos Elemer, Nov 14 2001

Status

approved