A113304 Primes that divide some central trinomial coefficient, A002426.

3, 7, 17, 19, 41, 43, 47, 73, 107, 109, 113, 131, 173, 179, 191, 193, 199, 233, 269, 277, 281, 283, 293, 307, 311, 347, 373, 383, 401, 409, 419, 421, 439, 443, 457, 467, 503, 509, 521, 547, 563, 569, 593, 613, 617, 631, 653, 673, 691, 701, 709, 719, 739, 743

Offset: 1

Author

T. D. Noe, Oct 24 2005

Keywords

• nonn

Comments

For primes less than 10^6, the density of these primes is near 0.3925.

Links

• G. C. Greubel, Table of n, a(n) for n = 1..1100

Crossrefs

Cf. A113302 (number of k for which prime(n) divides T(k)), A113303 (least k such that prime(n) divides T(k)).

Programs

Mathematica

nn=1000; a=b=1; t=Join[{1}, Table[c=((2n-1)b+3(n-1)a)/n; a=b; b=c; c, {n, 2, nn}]]; pLst={}; Do[p=Prime[n]; k=1; While[k
0, k++ ]; If[k