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%I #15 Nov 30 2019 17:22:19
%S 1,10,100,103,301,367,608,806,1000,1030,3010,3056,5630,6080,6703,6791,
%T 8060,9167,10000,10003,10275,10300,11241,12770,12939,13929,14112,
%U 17027,17502,20175,21921,22119,27501,30001,30067,30100,30616,31606,36700
%N Numbers n which are both happy (A007770) and bihappy (A257795) numbers.
%C This sequence is infinite, because it contains infinite subsequences (powers of 10, for example).
%H Giovanni Resta, <a href="/A257950/b257950.txt">Table of n, a(n) for n = 1..10000</a>
%F All 10^k are members of this sequence.
%F If n is a member each permutation of a set of pairs of digits gives another members (example 367 and 6703).
%F Placing two zeros between the sets of two digits gives another member.
%e 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.
%Y Cf. A007770, A257795.
%K nonn,base
%O 1,2
%A _Pieter Post_, May 14 2015
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