A078234 a(1) = 5, a(n+1) is the smallest multiple of a(n) using only prime digits (2,3,5,7).

5, 25, 75, 225, 3375, 57375, 2352375, 322275375, 27757255773375, 23322552325375373733375, 5272277223223332755233325327375733375

Offset

1,1

Comments

Sequence is infinite - see Comments in A078233. - Fung Cheok Yin (cheokyin_restart(AT)yahoo.com.hk), Sep 02 2006

Links

Table of n, a(n) for n=1..11.

Prog

(Python)
def pd(n): return set(str(n)) <= set("2357")  # has only prime digits
def aupton(terms, startat=5):
  alst = [startat]
  for n in range(2, terms+1):
    m = alst[-1]; km = 2*m
    while not pd(km): km += m
    alst.append(km)
  return alst
print(aupton(9)) # Michael S. Branicky, May 25 2021

Crossrefs

Cf. A078232, A078233, A078235, A078236.

Sequence in context: A147130 A154286 A331575 * A056374 A301912 A171272

Adjacent sequences: A078231 A078232 A078233 * A078235 A078236 A078237

Keyword

base,nonn,more

Author

Amarnath Murthy, Nov 23 2002

Extensions

More terms from Sascha Kurz, Jan 06 2003

a(10) from Robert Gerbicz, May 09 2008

a(11) from Michael S. Branicky, May 25 2021

Status

approved