|
|
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
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
|
|
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
|
|
|
KEYWORD
|
nonn,base
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|