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A265577 LCM-transform of Yellowstone permutation A098550. 2
1, 2, 3, 2, 3, 2, 5, 7, 1, 1, 5, 1, 1, 2, 1, 1, 1, 1, 3, 11, 13, 1, 1, 1, 1, 1, 1, 17, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 7, 19, 1, 1, 1, 1, 1, 1, 1, 23, 1, 1, 1, 1, 1, 1, 1, 3, 1, 29, 31, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..71.

A. Nowicki, Strong divisibility and LCM-sequences, arXiv:1310.2416 [math.NT], 2013.

A. Nowicki, Strong divisibility and LCM-sequences, Am. Math. Mnthly 122 (2015), 958-966.

MAPLE

LCMXfm:=proc(a) local L, i, n, g, b;

L:=nops(a);

g:=Array(1..L, 0); b:=Array(1..L, 0);

b[1]:=a[1]; g[1]:=a[1];

for n from 2 to L do g[n]:=ilcm(g[n-1], a[n]); b[n]:=g[n]/g[n-1]; od;

lprint([seq(b[i], i=1..L)]);

end;

# let t1 contain the first 100 terms of A098550

LCMXfm(t1);

MATHEMATICA

LCMXfm[a_List] := Module[{L = Length[a], b, g}, b[1] = g[1] = a[[1]]; b[_] = 0; g[_] = 0; Do[g[n] = LCM[g[n-1], a[[n]]]; b[n] = g[n]/g[n-1], {n, 2, L}]; Array[b, L]];

y[n_ /; n <= 3] := n; y[n_] := y[n] = For[k = 1, True, k++, If[ FreeQ[ Array[y, n-1], k], If[GCD[k, y[n-1]] == 1 && GCD[k, y[n-2]] > 1, Return[k]]]];

Yperm = Array[y, 100];

LCMXfm[Yperm] (* Jean-Fran├žois Alcover, Dec 03 2017 *)

CROSSREFS

Cf. A064413.

Other LCM-transforms are A061446, A265574, A265575, A265576.

Sequence in context: A120223 A282691 A346744 * A251103 A065559 A087317

Adjacent sequences:  A265574 A265575 A265576 * A265578 A265579 A265580

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Jan 02 2016

STATUS

approved

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Last modified July 6 11:37 EDT 2022. Contains 355110 sequences. (Running on oeis4.)