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A316348 a(n) is the smallest k > 1 such that gcd(k, m^k - m) = 1 for all m = 2,...,n. 1
35, 35, 77, 77, 143, 143, 143, 143, 299, 299, 323, 323, 323, 323, 437, 437, 667, 667, 667, 667, 899, 899, 899, 899, 899, 899, 1457, 1457, 1739, 1739, 1739, 1739, 1739, 1739, 1763, 1763, 1763, 1763, 2021, 2021, 2491, 2491, 2491, 2491, 3127, 3127, 3127, 3127, 3127 (list; graph; refs; listen; history; text; internal format)
OFFSET
2,1
COMMENTS
Conjecture: all the terms are in A121707.
From David A. Corneth, Aug 13 2018: (Start)
GCD(n, a(n)) = 1. a(n) is odd.
Is a(n) squarefree?
a(n+1) >= a(n) by definition. (End)
It seems that a(prime(n+1)-1) > a(prime(n)-1) for n > 1. - Thomas Ordowski, Aug 13 2018
LINKS
FORMULA
Conjecture: a(n) ~ n^2.
PROG
(PARI) isok(k, n)= {for (m=2, n, if (gcd(k, m^k - m) != 1, return (0)); ); return(1); }
a(n) = {my(k=2); while (! isok(k, n), k++); k; } \\ Michel Marcus, Aug 13 2018
CROSSREFS
Sequence in context: A257948 A142728 A316111 * A146205 A201067 A210320
KEYWORD
nonn
AUTHOR
Thomas Ordowski, Aug 13 2018
EXTENSIONS
More terms from Michel Marcus, Aug 13 2018
STATUS
approved

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Last modified May 30 18:38 EDT 2024. Contains 372971 sequences. (Running on oeis4.)