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

1,1

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

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<p && Mod[t[[k]], p]>0, k++ ]; If[k<p, AppendTo[pLst, p]], {n, PrimePi[nn]}]; pLst

Crossrefs

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

Sequence in context: A076194 A167168 A064699 * A194945 A093651 A181420

Adjacent sequences: A113301 A113302 A113303 * A113305 A113306 A113307

Keyword

nonn

Author

T. D. Noe, Oct 24 2005

Status

approved