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A339883 Values of Euler's totient phi for A050498. 2
24, 72, 25440, 33840, 38880, 48960, 99360, 123120, 208320, 458640, 510720, 519360, 532800, 583440, 596400, 622080, 663840, 838800, 846960, 873600, 893760, 942480, 1050480, 1065600, 1078800, 1163040 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

For the shown values the arithmetic progression with difference 6 has exactly 4 terms. Conjecture 1: this holds for all A050498 entries.

Conjecture 2: All a(n) are divisible by 24, starting with [1, 3, 1060, 1410, 1620, 2040, 4140, 5130, 8680, 19110, 21280, 21640, 22200, 24310, 24850, 25920, 27660, 34950, 35290, 36400, 37240, 39270, 43770, 44400, 44950, 48460, ...].

In the Lal and Gillard link only the first three A050498 values (with n <= 10^5) and their corresponding phi values are given.

LINKS

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

M. Lal and P. Gillard, On the Equation phi(n) = phi(n+k), Mathematics of Computation, Volume 26, Number 118 (1972) 579-584. [Eq. (4), Table 3, for k = 6, n <= 10^5]

David Wells, Curious and interesting numbers, Penguin Books, Revised edition, 1997 p. 112. [Gives under the number 72 the first three values of A050498 but with 76,236 instead of 76,326]

FORMULA

a(n) = A000010(A050498(n)), n >= 1.

CROSSREFS

Cf. A000010, A050498.

Sequence in context: A292353 A189540 A329077 * A042128 A043406 A044162

Adjacent sequences:  A339880 A339881 A339882 * A339884 A339885 A339887

KEYWORD

nonn

AUTHOR

Wolfdieter Lang, Jan 09 2021

STATUS

approved

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Last modified April 15 01:01 EDT 2021. Contains 342971 sequences. (Running on oeis4.)