|
%I #7 Jan 06 2013 17:30:30
%S 5,19,43,173
%N Primes of the form (1+2+...+m)/87 = A000217(m)/87.
%C Original definition: "Primes of the form : 1/x+2/x+3/x+4/x+5/x+6/x+7/x+..., x=87."
%C The corresponding m-values are m=29,57,86,173. It is clear that for m>2*87, T(m)/87 = m(m+1)/174 cannot be a prime, since then each factor in the numerator is larger than the denominator. See A154304 for further comments and PARI code. - _M. F. Hasler_, Jan 06 2013
%t lst={};s=0;Do[s+=n/87;If[Floor[s]==s,If[PrimeQ[s],AppendTo[lst,s]]],{n,0,4*9!}];lst
%o (PARI) d=87*2;for(m=1,999,(m^2+m)%d==0&isprime((m^2+m)/d)&print1(m",")) \\ print the m-values(!) - use A154304(87) to get A154302 as a vector. \\ - _M. F. Hasler_, Jan 06 2013
%Y Cf. A057570, A154293, A154296 - A154304.
%K nonn,fini,full,easy,bref
%O 1,1
%A _Vladimir Joseph Stephan Orlovsky_, Jan 06 2009
%E Edited by _M. F. Hasler_, Jan 06 2013
|
