OFFSET
1,2
COMMENTS
Note: a(n)=0 means either there is no such m, or 2^n+1 is a Fermat prime, A019434. However, no such prime is known for n>16 and a(n)>0 for all n < 25. Thus a(n)=0 will practically always mean that there's no such m.
MATHEMATICA
lmln[n_]:=Module[{m=n, c=2^n}, While[!PrimeQ[c+ 3^m]&&m>0, m--]; m]; Array[lmln, 80] (* Harvey P. Dale, Apr 05 2023 *)
PROG
(PARI) A159267(n)=forstep(m=n, 1, -1, ispseudoprime(2^n+3^m) & return(m))
CROSSREFS
KEYWORD
nonn
AUTHOR
M. F. Hasler, Apr 07 2009
STATUS
approved