A371278 - OEIS

A371278

Numbers k > 1 such that k / A054841(k) is an integer.

2, 4, 12, 16, 144, 192, 256, 1728, 3888, 4320, 6480, 7200, 11520, 13122, 14580, 15360, 20736, 36864, 49152, 65536, 107520, 344064, 384000, 589824, 691200, 1244160, 1259712, 1327104, 2211840, 2304960, 2963520, 2985984, 3932160, 3981312, 4478976, 4500000

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..36.

EXAMPLE

k = 144: A054841(144) = 24 because 144 = 3^2 * 2^4, 144/A054841(144) = 144/24 = 6, thus 144 is a term.

MATHEMATICA

q[n_] := Module[{f = FactorInteger[n]}, Divisible[n, Total[10^(PrimePi[f[[;; , 1]]] - 1) * f[[;; , 2]]]]]; q[1] = False; Select[Range[10^5], q] (* Amiram Eldar, Mar 17 2024 *)

PROG

(Python)

from sympy import factorint, primepi

def ok(n): return n > 1 and n%sum(e*10**(primepi(p)-1) for p, e in factorint(n).items()) == 0

print([k for k in range(10**4) if ok(k)]) # Michael S. Branicky, Mar 17 2024

CROSSREFS

Cf. A054841, A001146 (a subsequence).

Sequence in context: A097001 A233191 A192533 * A085931 A125885 A067929

Adjacent sequences: A371275 A371276 A371277 * A371279 A371280 A371281

KEYWORD

nonn

AUTHOR

Ctibor O. Zizka, Mar 17 2024

EXTENSIONS

More terms from Michel Marcus, Mar 17 2024

STATUS

approved