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A280966
Happy numbers which when squared give another happy number.
1
1, 7, 10, 28, 70, 91, 100, 167, 236, 280, 329, 379, 397, 638, 655, 656, 700, 709, 836, 899, 910, 1000, 1067, 1114, 1177, 1212, 1288, 1299, 1332, 1444, 1447, 1528, 1547, 1574, 1587, 1670, 1679, 1717, 1727, 1733, 1745, 1748, 1752, 1758, 1814, 1844, 1851, 2109
OFFSET
1,2
COMMENTS
If x is a member then so is 10*x. - Robert Israel, Jan 25 2017
LINKS
MAPLE
ishappy:= proc(n) option remember;
procname(convert(map(`^`, convert(n, base, 10), 2), `+`))
end proc:
ishappy(1):= true:
ishappy(37):= false:
select(t -> ishappy(t) and ishappy(t^2), [$1..10000]); # Robert Israel, Jan 25 2017
CROSSREFS
Cf. A007770.
Sequence in context: A240795 A058532 A370107 * A360430 A174466 A070422
KEYWORD
nonn,base
AUTHOR
Sam Turley, Jan 11 2017
STATUS
approved