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 A249105 Numbers n 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS 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. Cf. A003415, A210503, A230543, A249106, A249107, A249110. Sequence in context: A271385 A110763 A066352 * A249110 A051674 A132641 Adjacent sequences:  A249102 A249103 A249104 * A249106 A249107 A249108 KEYWORD nonn 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

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Last modified January 20 04:21 EST 2019. Contains 319323 sequences. (Running on oeis4.)