A277676 Numbers k such that d(k+2) > d(k+1), where d(m) is the number of digits in the base-m representation of m!.

2, 4, 5, 6, 8, 9, 10, 12, 13, 14, 16, 17, 18, 20, 21, 22, 23, 25, 26, 27, 29, 30, 31, 32, 34, 35, 36, 37, 39, 40, 41, 42, 44, 45, 46, 47, 49, 50, 51, 52, 53, 55, 56, 57, 58, 60, 61, 62, 63, 65, 66, 67, 68, 69, 71, 72, 73, 74, 76, 77, 78, 79, 80, 82, 83, 84

Offset

1,1

Comments

It has been checked for k = 2..50000 that if d(k+1) > d(k), then d(k+1) = d(k) + 1.

Links

Clark Kimberling, Table of n, a(n) for n = 1..1000

Formula

(See A277674.)

Mathematica

d = Differences@Array[Floor@Log[#, #!] &, 10000, 2]; (* Robert G. Wilson v, Oct 27 2016 *)
u = Flatten[Position[d, 0]]; (* A277675 *)
v = Flatten[Position[d, 1]]; (* A277676 *)

Prog

(PARI) d(n) = #digits(n!, n);
isok(n) = d(n+2) > d(n+1); \\ Michel Marcus, Oct 29 2016

Crossrefs

Cf. A000142, A060151, A277674, A277675.

Sequence in context: A047839 A285601 A139255 * A317551 A004773 A104401

Adjacent sequences: A277673 A277674 A277675 * A277677 A277678 A277679

Keyword

nonn,base,easy

Author

Clark Kimberling, Oct 26 2016

Status

approved