A097227 Numbers m such that m = prime(d_1) * prime(d_2) * ... * prime(d_k), where d_1 d_2 ... d_k is the decimal expansion of m.

14, 154, 1196, 279174

Offset

1,1

Comments

a(n) !== 1 (mod 10). No other terms below 10^44. - Chai Wah Wu, Aug 10 2017

Links

Table of n, a(n) for n=1..4.

Example

279174 = prime(2)*prime(7)*prime(9)*prime(1)*prime(7)*prime(4) so 279174 is in the sequence.

Mathematica

v={}; Do[h=IntegerDigits[n]; l=Length[h]; p=Product[h[[k]], {k, l}]; If[p>0&&Product[Prime[h[[k]]], {k, l}]==n, v=Append[v, n]; Print[v]], {n, 40000000}]

Prog

(Python)
from functools import reduce
from operator import mul
from itertools import combinations_with_replacement
A097227_list, ptuple = [], (2, 3, 5, 7, 11, 13, 17, 19, 23)
for l in range(1, 12):
    for d in combinations_with_replacement(range(1, 10), l):
        n = reduce(mul, (ptuple[i-1] for i in d))
        if n < 10**l and tuple(sorted((int(x) for x in str(n)))) == d:
            A097227_list.append(n) # Chai Wah Wu, Aug 10 2017

Crossrefs

Cf. A097228.

Subsequence of A329711.

Sequence in context: A016215 A329711 A290675 * A229315 A257288 A125426

Adjacent sequences: A097224 A097225 A097226 * A097228 A097229 A097230

Keyword

base,more,nonn

Author

Farideh Firoozbakht, Aug 12 2004

Status

approved