

A154296


Primes of the form (1+2+3+...+m)/15 = A000217(m)/15, for some m.


9




OFFSET

1,1


COMMENTS

Original definition : Primes of the form 1/x+2/x+3/x+4/x+5/x+6/x+7/x+..., x=15.
The corresponding mvalues are m=9, 14, 29, 30. It is clear that for m>30, T(m)/15 = m(m+1)/30 cannot be a prime.  M. F. Hasler, Dec 31 2012
All of the sequences A154296, ..., A154304 could or should be grouped together in a single ("fuzzy"?) table. It would be more interesting to have the function f(n) which gives the *number* of primes of the form T(k)/n.  M. F. Hasler, Jan 06 2013


LINKS

Table of n, a(n) for n=1..4.


MATHEMATICA

lst={}; s=0; Do[s+=n/15; If[Floor[s]==s, If[PrimeQ[s], AppendTo[lst, s]]], {n, 0, 9!}]; lst
Select[(Accumulate[Range[200]])/15, PrimeQ] (* Harvey P. Dale, Oct 30 2011 *)


PROG

(PARI) select(x>denominator(x)==1 & isprime(x), vector(30, m, m^2+m)/30) \\  M. F. Hasler, Dec 31 2012


CROSSREFS

Cf. A057570, A154293, A154297, A154298, A154299, A154300, A154301, A154302, A154303, A154304.
Sequence in context: A018989 A325258 A073126 * A038900 A068485 A019352
Adjacent sequences: A154293 A154294 A154295 * A154297 A154298 A154299


KEYWORD

nonn,fini,full,easy


AUTHOR

Vladimir Joseph Stephan Orlovsky, Jan 06 2009


EXTENSIONS

Edited by M. F. Hasler, Dec 31 2012


STATUS

approved



