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A164770
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Numbers k with the property that the average digit of k^2 is 2.
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9
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145, 152, 179, 190, 251, 3182, 3190, 3199, 3245, 3290, 3335, 3362, 3380, 3470, 3479, 3496, 3550, 3649, 3650, 3749, 3821, 4001, 4010, 4100, 4495, 4496, 4540, 4550, 4585, 4595, 4639, 4649, 4810, 4820, 4910, 4990, 5701, 5710, 5755, 5800, 5900, 6350, 6404
(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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There are 6368 such k's < 10^7: see link to 15217.html.
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LINKS
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Harvey P. Dale, Table of n, a(n) for n = 1..2500
Zak Seidov, Average digit of n^2 is 2.
Zak Seidov, Case with trailing zeros.
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EXAMPLE
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145 is a term because 145^2 = 21025 and (2 + 1 + 0 + 2 + 5)/5 = 2.
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MATHEMATICA
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Select[Range[6500], Mean[IntegerDigits[#^2]]==2&] (* Harvey P. Dale, May 10 2021 *)
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PROG
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(PARI) dsum(n)={my(s=0); while(n>9, s+=n%10; n\=10); s+n}; for(n=1, 1e6, if(dsum(n^2)/#Str(n^2)==2, print1(n", ")))
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CROSSREFS
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Sequence in context: A099648 A043652 A296889 * A159777 A326258 A051414
Adjacent sequences: A164767 A164768 A164769 * A164771 A164772 A164773
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KEYWORD
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base,nonn,easy
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AUTHOR
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Zak Seidov, Aug 26 2009
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EXTENSIONS
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Program by Charles R Greathouse IV, Nov 01 2009
Edited by Charles R Greathouse IV, Mar 23 2010
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STATUS
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approved
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