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A046834
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Internal digits of n^2 include digits of n as subsequence.
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2
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50, 60, 250, 500, 600, 760, 1050, 2050, 2500, 3050, 3628, 3710, 3760, 3792, 4050, 4410, 5000, 5010, 5050, 5060, 5250, 6000, 6010, 6050, 6250, 6760, 7050, 7560, 7600, 8050, 8250, 8260, 8882, 9050, 9460, 10050, 10500, 14650, 14651, 20050, 20500
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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COMMENTS
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LINKS
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EXAMPLE
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a(7) = 1050 is a term because 1050^2 = 1102500; remove the first and last to get internal digits 10250, and 1050 is a subsequence of 10250. - Robert Israel, May 07 2020
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MAPLE
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filter:= n -> StringTools:-IsSubSequence(sprintf("%d", n), sprintf("%d", n^2)[2..-2]):
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PROG
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(Python)
from itertools import count, islice
def A046834_gen(startvalue=1): # generator of terms >= startvalue
for k in count(max(startvalue, 1)):
c = iter(str(k**2)[1:-1])
if all(map(lambda b:any(map(lambda a:a==b, c)), str(k))):
yield k
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CROSSREFS
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KEYWORD
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nonn,base,easy
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AUTHOR
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STATUS
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approved
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