|
|
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.
|
|
10
|
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
a(n) !== 1 (mod 10). No other terms below 10^44. - Chai Wah Wu, Aug 10 2017
|
|
LINKS
|
|
|
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:
|
|
CROSSREFS
|
|
|
KEYWORD
|
base,more,nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|