A217425 Numbers of the form 5^r*7^s whose decimal representations are such that each digit 0-9 appears a prime number of times.

97402668820327149658203125, 81209257154451887573232591061530625, 13375863052949754169544537548117223100875, 4587921027161765680153776379004207523600125, 2478309849684200670569842256516437530517578125

Offset: 1

Author

James G. Merickel, Oct 05 2012

Keywords

• nonn
• base
• less

Comments

See the formula section for more data, and other sequences in cross-reference for motivation and similar sequences.

Examples

			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.

Formula

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