

A281302


Largest nonnegative k such that binomial(2*c1, c1) == 1 (mod c^k), where c is the nth composite number.


3



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OFFSET

1


COMMENTS

a(n) > 0 if c is either a term of A168363 or a term of A228562.
If c is a term of A267824, then a(n) > 1.
If there is a composite c that is a counterexample to the converse of Wolstenholme's theorem, that composite has a(i) > 2, where i is the index of c in A002808.


LINKS

Antti Karttunen, Table of n, a(n) for n = 1..25000
Wikipedia, Wolstenholme's theorem.


PROG

(PARI) forcomposite(c=1, , my(k=0); while(Mod(binomial(2*c1, c1), c^k)==1, k++); print1(k1, ", "))


CROSSREFS

Cf. A002808, A168363, A244919, A267824.
Sequence in context: A194670 A130543 A193243 * A160753 A328981 A024360
Adjacent sequences: A281299 A281300 A281301 * A281303 A281304 A281305


KEYWORD

nonn


AUTHOR

Felix FrÃ¶hlich, Jan 21 2017


EXTENSIONS

More terms from Antti Karttunen, Nov 08 2018


STATUS

approved



