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A390320

Positive integers (not multiples of 10 and greater than 1) whose constant congruence speed is greater than the maximum of the constant congruence speeds of all their prime factors (see A373387 for the definition of "constant congruence speed").

15, 18, 24, 25, 26, 32, 51, 55, 57, 65, 68, 74, 76, 82, 93, 95, 99, 105, 118, 124, 126, 132, 135, 143, 145, 174, 175, 176, 182, 185, 201, 207, 215, 218, 225, 226, 232, 243, 249, 255, 265, 268, 274, 276, 282, 295, 299, 305, 318, 324, 326, 332, 335, 345, 351

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

This sequence, by definition, does not include any prime number.

REFERENCES

Marco Ripà, La strana coda della serie n^n^...^n, Trento, UNI Service, Nov 2011. ISBN 978-88-6178-789-6.

LINKS

Table of n, a(n) for n=1..55.

Marco Ripà, The congruence speed formula, Notes on Number Theory and Discrete Mathematics, 2021, 27(4), 43-61.

Marco Ripà and Gabriele di Pietro, A Compact Notation for Peculiar Properties Characterizing Integer Tetration, Zenodo, April 2025.

Marco Ripà and Luca Onnis, Number of stable digits of any integer tetration, Notes on Number Theory and Discrete Mathematics, 2022, 28(3), 441-457.

Gabriele Di Pietro, Congruence speed greater than their factors, Zenodo, December 2026

EXAMPLE

Constant congruence speed of a(1)=15 is 4 that is greater than the maximum of the constant congruence speed of 5 and 3 (prime factors of a(1)=15). In fact the constant congruence speed of 5 is 2 and the constant congruence speed of 3 is 1.

PROG

(Python) # See Links.

CROSSREFS

Cf. A317905, A373387, A389432, A389979, A389980, A389981.

Sequence in context: A290015 A354818 A390601 * A389981 A384947 A274979

Adjacent sequences: A390317 A390318 A390319 * A390321 A390322 A390323

KEYWORD

nonn,base

AUTHOR

Gabriele Di Pietro and Marco Ripà, Dec 04 2025

STATUS

approved

URL: https://oeis.org/A390320

⇱ A390320 - OEIS