A194041 - OEIS

A194041

Lucky numbers which are also unhappy numbers.

3, 9, 15, 21, 25, 33, 37, 43, 51, 63, 67, 69, 73, 75, 87, 93, 99, 105, 111, 115, 127, 135, 141, 151, 159, 163, 169, 171, 189, 195, 201, 205, 211, 223, 231, 235, 237, 241, 259, 261, 267, 273, 283, 285, 289, 297, 303, 307, 321, 327, 339, 349, 357, 361, 385, 393

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OFFSET

1,1

COMMENTS

An unhappy number is a number that is not happy (A007770) i.e., a number n such that iterating this sum-of-squared-digits map starting with n never reaches the number 1. Many asymptotic properties of the prime numbers are shared by the lucky numbers.

LINKS

Nathaniel Johnston, Table of n, a(n) for n = 1..1000

Eric W. Weisstein, Unhappy Number

Eric W. Weisstein, Lucky Number

FORMULA

A000959 INTERSECTION A031177. {k such that k is in A000959 and k is not in A007770}.

CROSSREFS

Cf. A000959, A007770, A031177.

Sequence in context: A307202 A162488 A324298 * A029506 A299790 A030594

Adjacent sequences: A194038 A194039 A194040 * A194042 A194043 A194044

KEYWORD

nonn,easy

AUTHOR

Jonathan Vos Post, Aug 12 2011

STATUS

approved