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A070115 Numbers m such that [A070080(m), A070081(m), A070082(m)] is an isosceles integer triangle. 9
1, 2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 14, 15, 16, 18, 19, 22, 23, 24, 26, 27, 28, 31, 32, 34, 35, 38, 39, 40, 43, 46, 47, 48, 51, 52, 54, 55, 58, 61, 63, 64, 65, 68, 71, 72, 73, 76, 81, 82, 84, 85, 88, 91, 93, 94, 95, 98, 103, 104, 107, 108 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Jean-François Alcover, Table of n, a(n) for n = 1..365

Reinhard Zumkeller, Integer-sided triangles

EXAMPLE

26 is a term because [A070080(26), A070081(26), A070082(26)] = [4=4<6].

MATHEMATICA

m = 55 (* max perimeter *);

sides[per_] := Select[Reverse /@ IntegerPartitions[per, {3}, Range[ Ceiling[per/2]]], #[[1]] < per/2 && #[[2]] < per/2 && #[[3]] < per/2 &];

triangles = DeleteCases[Table[sides[per], {per, 3, m}], {}] // Flatten[#, 1]& // SortBy[Total[#] m^3 + #[[1]] m^2 + #[[2]] m + #[[1]] &];

Position[triangles, {a_, a_, b_} | {a_, b_, b_}] // Flatten (* Jean-François Alcover, Oct 12 2021 *)

CROSSREFS

Cf. A059169, A070116, A070117, A070124, A070125, A070126, A070133, A070134, A070135.

Sequence in context: A187226 A026470 A014133 * A073571 A328242 A294295

Adjacent sequences:  A070112 A070113 A070114 * A070116 A070117 A070118

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, May 05 2002

STATUS

approved

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Last modified June 29 17:41 EDT 2022. Contains 354913 sequences. (Running on oeis4.)