A069518 Geometric mean of digits = 4 and digits are in nondecreasing order.

4, 28, 44, 188, 248, 444, 1488, 2288, 2448, 4444, 12888, 14488, 22488, 24448, 44444, 118888, 124888, 144488, 222888, 224488, 244448, 444444, 1148888, 1228888, 1244888, 1444488, 2224888, 2244488, 2444448, 4444444, 11288888, 11448888, 12248888, 12444888

Offset

1,1

Comments

No number is obtainable by permuting the digits of other members - only one with ascending order of digits is included.

Links

Michael S. Branicky, Table of n, a(n) for n = 1..10000

Example

1488 is a term but 1848 is not.

Mathematica

a = {}; b = 4; Do[c = Apply[ Times, IntegerDigits[n]]/b^Floor[ Log[10, n] + 1]; If[c == 1 && Position[a, FromDigits[ Sort[ IntegerDigits[n]]]] == {}, Print[n]; a = Append[a, n]], {n, 1, 10^7}]

Prog

(Python)
from math import prod
from sympy.utilities.iterables import multiset_combinations
def auptod(terms):
  n, digits, alst, powsexps2 = 0, 1, [], [(1, 0), (2, 1), (4, 2), (8, 3)]
  while n < terms:
    target = 4**digits
    mcstr = "".join(str(d)*(digits//max(1, r//2)) for d, r in powsexps2)
    for mc in multiset_combinations(mcstr, digits):
      if prod(map(int, mc)) == target:
        n += 1
        alst.append(int("".join(mc)))
        if n == terms: break
    else: digits += 1
  return alst
print(auptod(34)) # Michael S. Branicky, Apr 28 2021

Crossrefs

Cf. A061428, A069512, A069516.

Sequence in context: A307046 A179279 A061428 * A151912 A307135 A101002

Adjacent sequences: A069515 A069516 A069517 * A069519 A069520 A069521

Keyword

nonn,base

Author

Amarnath Murthy, Mar 30 2002

Extensions

Edited and extended by Robert G. Wilson v, Apr 01 2002

Name edited and a(31) and beyond from Michael S. Branicky, Apr 28 2021

Status

approved