login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A113305 Primes that do not divide any central trinomial coefficient, A002426. 4
2, 5, 11, 13, 23, 29, 31, 37, 53, 59, 61, 67, 71, 79, 83, 89, 97, 101, 103, 127, 137, 139, 149, 151, 157, 163, 167, 181, 197, 211, 223, 227, 229, 239, 241, 251, 257, 263, 271, 313, 317, 331, 337, 349, 353, 359, 367, 379, 389, 397, 431, 433, 449, 461, 463, 479 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

For primes less than 10^6, the density of these primes is near 0.6075.

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..1600

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: A045361 A276660 A086081 * A095078 A062572 A215214

Adjacent sequences:  A113302 A113303 A113304 * A113306 A113307 A113308

KEYWORD

nonn

AUTHOR

T. D. Noe, Oct 24 2005

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified February 23 23:56 EST 2018. Contains 299595 sequences. (Running on oeis4.)