S000724


Numbers n such that binomial(2n,n) is not divisible by 17, 19, 23, and 29.

0, 1, 2, 3, 4, 5, 6, 7, 8, 119, 120, 121, 122, 123, 1160, 1161, 1197, 1198, 1224, 1225, 1805, 1827, 30345, 30346, 30347, 30348, 30363, 30364, 30365, 30366, 30367, 30368, 30369, 30370, 36524, 3129683, 3129684, 3129685, 3129686, 3129687, 3129688, 3129689, 3130231

1

S000724

The sequence for the 3-5-7-11 case has only 3 terms. These related five sequences (S000720-S000724) provide more insight to the problem. Using the analysis of the Pomerance paper, this sequence is expected to be infinite.

T. D. Noe, Plot of 263 terms

T. D. Noe, Table of 263 terms

Carl Pomerance, Divisors of the middle binomial coefficient, Amer. Math. Monthly, 122 (2015), pp. 636-644.

(Mma) lim = 1000000; Intersection[Table[FromDigits[IntegerDigits[k, 9], 17], {k, 0, lim}], Table[FromDigits[IntegerDigits[k, 10], 19], {k, 0, lim}], Table[FromDigits[IntegerDigits[k, 12], 23], {k, 0, lim}], Table[FromDigits[IntegerDigits[k, 15], 29], {k, 0, lim}]]

Cf. A151750 (the 3,5,7,11 case), S000720-S000723.

nonn

T. D. Noe, Oct 16 2015

© Tony D Noe 2014-2015