OFFSET
1,1
COMMENTS
Sánchez Garza and Treviño proved the counting function for this sequence is asymptotic to x/log x. See link.
LINKS
M. Sánchez Garza and E. Treviño, On a sequence related to the factoradic representation of an integer, Journal of Integer Sequences Vol. 24 (2021), Article 21.8.5.
MATHEMATICA
j[r_] := j[r] = Module[{k = 1}, While[k! <= k^(r - 1), k++]; k];
jPrimes = {}; Do[If[j[r + 1] - j[r] == 2, AppendTo[jPrimes, r], 0], {r, 1, 2500}]
PROG
(PARI) f(n) = my(k=1); while (k^n >= k!, k++); k; \\ A230319
isok(n) = f(n) - f(n-1) == 2; \\ Michel Marcus, Jan 27 2021
CROSSREFS
KEYWORD
nonn
AUTHOR
Enrique Treviño, Jan 27 2021
STATUS
approved