Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #5 May 26 2024 01:25:25
%S 7,11,19,43,47,127,131,163,179,191,199,263,347,367,419,431,443,491,
%T 503,523,571,619,691,727,743,787,839,863,1051,1087,1091,1123,1291,
%U 1319,1367,1451,1487,1499,1571,1579,1583,1667,1723,1783,1823,1931,1951,2003,2039
%N Primes p such that m=(p-1)/2 is the least number such that p divides m!+1.
%C The graph of A073944 shows two prominent curves. This sequence gives the primes on the lower curve. Primes on the upper curve are in sequence A154554.
%H T. D. Noe, <a href="/A154555/b154555.txt">Table of n, a(n) for n=1..1000</a>
%t Rest[Reap[Do[p=Prime[i]; f=1; m=1; While[f=Mod[f*m,p]; f+1<p, m++ ]; If[m==(p-1)/2, Sow[p]], {i,400}]]][[1,1]]
%Y Cf. A073944, A154554.
%K nonn
%O 1,1
%A _T. D. Noe_, Jan 12 2009