This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A154303 #8 Jan 06 2013 17:22:49
%S A154303 7,11,179,181
%N A154303 Primes of the form (1+2+...+m)/90 = A000217(m)/90.
%C A154303 Original definition: "Primes of the form : 1/x+2/x+3/x+4/x+5/x+6/x+7/x+..., x=90."
%C A154303 The corresponding m-values are m=35,44,179,180. It is clear that for m>180, T(m)/90 = m(m+1)/180 cannot be a prime, since then each factor in the numerator is larger than the denominator. 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
%t A154303 lst={};s=0;Do[s+=n/90;If[Floor[s]==s,If[PrimeQ[s],AppendTo[lst,s]]],{n,0,5*9!}];lst
%o A154303 (PARI) d=90*2;for(m=1,999,(m^2+m)%d==0&isprime((m^2+m)/d)&print1(m",")) \\ print the m-values(!) - use A154304(90) to get A154303 as a list/vector. \\ - _M. F. Hasler_, Jan 06 2013
%Y A154303 Cf. A057570, A154293, A154296 - A154304.
%K A154303 nonn,fini,full,easy,bref
%O A154303 1,1
%A A154303 _Vladimir Joseph Stephan Orlovsky_, Jan 06 2009
%E A154303 Edited by _M. F. Hasler_, Jan 06 2013