A257950 Numbers n which are both happy (A007770) and bihappy (A257795) numbers.
1, 10, 100, 103, 301, 367, 608, 806, 1000, 1030, 3010, 3056, 5630, 6080, 6703, 6791, 8060, 9167, 10000, 10003, 10275, 10300, 11241, 12770, 12939, 13929, 14112, 17027, 17502, 20175, 21921, 22119, 27501, 30001, 30067, 30100, 30616, 31606, 36700
Offset: 1
Examples
367 is member of this sequence because 367 = 3^2+6^2+7^2= 94 => 9^2+4^2 = 97 => 9^2+7^2 = 130 => 1^2+3^2+0^2 = 10 => 1^2+0^2 = 1, so after five iterations 367 reaches 1. And 3^2+67^2 = 4498 => 44^2+98^2= 11540 => 1^2+15^2+40^2 = 1826 => 18^2+26^2 = 1000 => 10^2+0^2 = 100 =>1^2+0^2 = 1, so in 6 iterations 367 reaches 1.
Links
- Giovanni Resta, Table of n, a(n) for n = 1..10000
Formula
All 10^k are members of this sequence.
If n is a member each permutation of a set of pairs of digits gives another members (example 367 and 6703).
Placing two zeros between the sets of two digits gives another member.
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