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A249105
Numbers that form a Pythagorean 5-tuple with their first three arithmetic derivatives.
3
4, 27, 1808, 3125, 12204, 12707, 82377, 269827, 823543, 1412500, 7089739, 9534375, 46873785, 78192979, 372241436
OFFSET
1,1
EXAMPLE
First three arithmetic derivatives of 1808 are 3632, 7280, 17616 and sqrt(1808^2 + 3632^2 + 7280^2 + 17616^2) = 19488.
MAPLE
with(numtheory);
Dr:=proc(w) local x, p; x:=w*add(op(2, p)/op(1, p), p=ifactors(w)[2]); end:
P:=proc(q, h) local a, b, k, n; for n from 2 to q do a:=n; b:=n^2;
for k from 1 to h do a:=Dr(a); b:=b+a^2; od; if type(sqrt(b), integer) then print(n);
fi; od; end: P(10^9, 3);
CROSSREFS
A051674 is a subsequence.
Sequence in context: A110763 A066352 A357561 * A249110 A348329 A051674
KEYWORD
nonn,more
AUTHOR
Paolo P. Lava, Oct 21 2014
EXTENSIONS
a(13) from Ray Chandler, Dec 23 2016
a(14) from Ray Chandler, Dec 24 2016
a(15) from Ray Chandler, Jan 08 2017
STATUS
approved