

A217425


Numbers of the form 5^r*7^s whose decimal representations are such that each digit 09 appears a prime number of times.


13



97402668820327149658203125, 81209257154451887573232591061530625, 13375863052949754169544537548117223100875, 4587921027161765680153776379004207523600125, 2478309849684200670569842256516437530517578125
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OFFSET

1,1


COMMENTS

See the formula section for more data, and other sequences in crossreference for motivation and similar sequences.


LINKS

Table of n, a(n) for n=1..5.


FORMULA

A217425(n) = 5^A217426(n) * 7^A217427(n).


EXAMPLE

A217426(1)=13 and A217427(1)=20, so this sequence's first term is 5^13 * 7^20. It has two copies each of the digits 1, 3, 4, 5, 7 and 9; three each of 0's, 6's and 8's; and five 2's.


CROSSREFS

Cf. A217854, A217426, A217427, A217404, A217407, A217410, A217413, A217416, A217419, A217422, A217428, A217431.
Sequence in context: A338953 A272520 A265913 * A214266 A175274 A095446
Adjacent sequences: A217422 A217423 A217424 * A217426 A217427 A217428


KEYWORD

nonn,base,less


AUTHOR

James G. Merickel, Oct 05 2012


STATUS

approved



