A381239 Primes of the form Sum_{k >= 0} floor(m/5^k) for some number m.

2, 3, 7, 13, 19, 31, 37, 41, 43, 47, 53, 59, 71, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 181, 191, 193, 197, 199, 211, 227, 233, 239, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 313, 331, 337, 347, 349, 353, 359

Offset: 1

Author

Clark Kimberling, Mar 09 2025

Keywords

• nonn

Examples

			floor(16/1) + floor(16/5) = 19, so 19 is in the sequence.
		

Crossrefs

Cf. A191610, A380662.

Programs

Mathematica

f[n_] := Sum[Floor[n/5^k], {k, 0, Floor[Log[5, n]]}]  (* A191610 *)
u=Select[Range[400], PrimeQ[f[#]] &]
Map[f, u]