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A039914 Smallest k>1 such that k(p-1)-1 is divisible by p^2, p=n-th prime. 2
5, 5, 19, 41, 109, 155, 271, 341, 505, 811, 929, 1331, 1639, 1805, 2161, 2755, 3421, 3659, 4421, 4969, 5255, 6161, 6805, 7831, 9311, 10099, 10505, 11341, 11771, 12655, 16001, 17029, 18631, 19181, 22051, 22649, 24491, 26405, 27721, 29755, 31861 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
a(1)=5 because 5(2-1)-1=4 is divisible by 2^2.
PROG
(PARI) a(n) = {my(p = prime(n), k = 2); while ((k*(p-1)-1) % p^2, k++); k; } \\ Michel Marcus, Sep 28 2013
CROSSREFS
Cf. A039678.
A306190 is an essentially identical sequence.
Sequence in context: A145937 A246983 A305514 * A274910 A370547 A201803
KEYWORD
nonn
AUTHOR
EXTENSIONS
Added constraint on k to the definition, otherwise a(1)=1 - R. J. Mathar, Oct 10 2010
STATUS
approved

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Last modified February 28 20:40 EST 2024. Contains 370400 sequences. (Running on oeis4.)