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A036944 Smallest n-digit prime containing only the digits 4 and 7, or 0 if no such prime exists. 2
7, 47, 0, 4447, 44777, 0, 4444747, 44447747, 0, 4444444447, 44444444747, 0, 4444444447777, 44444447447447, 0, 4444444447447777, 44444444444444477, 0, 4444444444444444777, 44444444444444444447, 0, 4444444444444444444747, 44444444444444444444477, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
MATHEMATICA
Flatten[Table[Select[FromDigits/@Tuples[{4, 7}, n], PrimeQ, 1], {n, 22}]/.{}->{0}] (* Harvey P. Dale, Jun 28 2012 *)
CROSSREFS
Sequence in context: A352693 A197754 A000823 * A068640 A089725 A086040
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Jan 04 1999
STATUS
approved

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Last modified March 28 14:38 EDT 2024. Contains 371254 sequences. (Running on oeis4.)