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A198409 Positions in sequences A198384, A198385 and A198386 to indicate triples of squares in arithmetic progression, that are not multiples of earlier triples. 15
1, 3, 5, 7, 10, 13, 15, 23, 24, 26, 30, 35, 39, 42, 45, 47, 51, 54, 62, 69, 70, 72, 83, 84, 88, 97, 98, 102, 107, 114, 115, 124, 126, 129, 136, 141, 142, 143, 156, 157, 167, 169, 172, 177, 181, 188, 191, 201, 205, 208, 214, 218, 229, 230, 237, 244, 249, 253 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
A198435(n) = A198384(a(n)); A198439(n) = A198388(a(n));
A198436(n) = A198385(a(n)); A198440(n) = A198389(a(n));
A198437(n) = A198386(a(n)); A198441(n) = A198390(a(n));
A198438(n) = A198387(a(n)).
LINKS
Reinhard Zumkeller, Table of initial values
FORMULA
MATHEMATICA
wmax = 1000;
triples[w_] := Reap[Module[{u, v}, For[u = 1, u < w, u++, If[IntegerQ[v = Sqrt[(u^2 + w^2)/2]], Sow[{u^2, v^2, w^2}]]]]][[2]];
tt = Flatten[DeleteCases[triples /@ Range[wmax], {}], 2];
Position[tt, t_List /; SquareFreeQ[GCD@@t]] // Flatten (* Jean-François Alcover, Oct 24 2021 *)
PROG
(Haskell)
import Data.List (elemIndices)
a198409 n = a198409_list !! (n-1)
a198409_list = map (+ 1) $ elemIndices 1 $ map a008966 $
zipWith gcd a198384_list $ zipWith gcd a198385_list a198386_list
CROSSREFS
Sequence in context: A050090 A152004 A298862 * A330072 A213510 A130257
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Oct 25 2011
STATUS
approved

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Last modified July 18 13:57 EDT 2024. Contains 374378 sequences. (Running on oeis4.)