

A214584


Integers whose decimal representation has only digits in {4,5,7}.


2



4, 5, 7, 44, 45, 47, 54, 55, 57, 74, 75, 77, 444, 445, 447, 454, 455, 457, 474, 475, 477, 544, 545, 547, 554, 555, 557, 574, 575, 577, 744, 745, 747, 754, 755, 757, 774, 775, 777, 4444, 4445, 4447, 4454, 4455, 4457, 4474, 4475, 4477, 4544, 4545, 4547, 4554, 4555, 4557, 4574, 4575, 4577, 4744
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OFFSET

1,1


COMMENTS

These could be called crooked numbers. Integers all of whose numerals are written (san serif) with at least one right or acute angle. The subsequence of crooked primes begins: 5, 7, 47, 457, 547, 557, 577, 757.
Exponential density 0.477... = log 3/log 10.  Charles R Greathouse IV, Jul 22 2012


LINKS

Table of n, a(n) for n=1..58.
Index entries for 10automatic sequences.


CROSSREFS

Cf. A072960 (numbers using only the curved digits 0, 3, 6, 8 and 9).
Sequence in context: A123368 A292164 A178439 * A198131 A200387 A082468
Adjacent sequences: A214581 A214582 A214583 * A214585 A214586 A214587


KEYWORD

nonn,base,easy


AUTHOR

Jonathan Vos Post, Jul 21 2012


STATUS

approved



