A070132 -id:A070132 - cp's OEIS frontend

A070127 Numbers n such that [A070080(n), A070081(n), A070082(n)] is an obtuse integer triangle.

5, 8, 13, 14, 20, 21, 25, 26, 29, 30, 32, 36, 37, 41, 42, 44, 49, 50, 52, 56, 57, 59, 61, 62, 66, 67, 69, 74, 75, 77, 78, 79, 80, 82, 86, 87, 89, 91, 96, 97, 99, 100, 101, 102, 104, 105, 110, 111, 113, 115, 118, 122, 123, 125, 126, 127

Offset: 1

Reinhard Zumkeller, May 05 2002

nonn

			a(10)=30: [A070080(30), A070081(30), A070082(30)]=[3,5,7], A070085(30)=3^2+5^2-7^2=9+25-49=-15<0.

Jean-François Alcover, Table of n, a(n) for n = 1..724
R. Zumkeller, Integer-sided triangles

Cf. A070101, A070129, A070130, A070131, A070132, A070133, A070134, A070135, A070128, A070085.

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_, b_, c_} /; a^2 + b^2 - c^2 < 0] // Flatten (* Jean-François Alcover, Oct 11 2021 *)

A070112 Numbers n such that [A070080(n), A070081(n), A070082(n)] is a scalene integer triangle.

Original entry on oeis.org

8, 13, 17, 20, 21, 25, 29, 30, 33, 36, 37, 41, 42, 44, 45, 49, 50, 53, 56, 57, 59, 60, 62, 66, 67, 69, 70, 74, 75, 77, 78, 79, 80, 83, 86, 87, 89, 90, 92, 96, 97, 99, 100, 101, 102, 105, 106, 110, 111, 113, 114, 115, 116, 119, 122

Offset: 1

Reinhard Zumkeller, May 05 2002

nonn

			a(17)=50: [A070080(50), A070081(50), A070082(50)]=[4<6<8].

Jean-François Alcover, Table of n, a(n) for n = 1..920
Reinhard Zumkeller, Integer-sided triangles

Cf. A005044, A070113, A070114, A070121, A070122, A070123, A070130, A070131, A070132.

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_, b_, c_} /; a < b < c] // Flatten (* Jean-François Alcover, Oct 12 2021 *)

A070111 Numbers k such that [A070080(k), A070081(k), A070082(k)] is an integer triangle with prime sides.

Original entry on oeis.org

3, 5, 6, 9, 14, 16, 22, 30, 34, 35, 43, 46, 63, 84, 101, 109, 124, 133, 153, 159, 163, 170, 189, 193, 201, 234, 240, 286, 297, 328, 334, 350, 352, 382, 392, 410, 444, 450, 454, 472, 478, 479, 515, 519, 527, 542, 544, 597, 603, 621, 629, 688, 708, 714, 771, 777, 795, 799, 811, 817, 868, 878, 900, 907, 911

Offset: 1

Reinhard Zumkeller, May 05 2002

nonn

			35 is a term: [A070080(35), A070081(35), A070082(35)]=[2,7,7].

Reinhard Zumkeller, Integer-sided triangles

Cf. A070088, A070114, A070117, A070120, A070123, A070126, A070129, A070132, A070135.

m = 50 (* 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_, b_, c_} /; AllTrue[{a, b, c}, PrimeQ]] // Flatten (* Jean-François Alcover, Oct 04 2021 *)

More terms from Jean-François Alcover, Oct 04 2021

A070105 Number of integer triangles with perimeter n and prime side lengths which are obtuse and scalene.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 2, 0, 1, 0, 2, 0, 1, 0, 2, 0, 0, 0, 3, 0, 1, 0, 1, 0, 2, 0, 0, 0, 0, 0, 3, 0, 1, 0, 3, 0, 4, 0, 3, 0, 1, 0, 1, 0, 1, 0, 1, 0, 2, 0, 3, 0, 1, 0, 5, 0, 4, 0, 5, 0, 5, 0

Offset: 1

Reinhard Zumkeller, May 05 2002

a(n) = 0 if n is even. - Robert Israel, Jul 26 2024

Robert Israel, Table of n, a(n) for n = 1..10000
R. Zumkeller, Integer-sided triangles

Cf. A070080, A070081, A070082, A070101, A005044, A070088, A070090, A070103, A024156, A070132.

f:= proc(n) local a,b,q,bmin,bmax,t;
  t:= 0;
  if n::even then return 0 fi;
  for a from 1 to n/3 by 2 do
    if not isprime(a) then next fi;
    bmin:= max(a+1,(n+1)/2-a); if bmin::even then bmin:= bmin+1 fi;
    q:= (n^2-2*n*a)/(2*(n-a));
    if q::integer then bmax:= min((n-a)/2, q-1) else bmax:= min((n-a)/2, floor(q)) fi;
    t:= t + nops(select(b -> isprime(b) and isprime(n-a-b), [seq(b,b=bmin .. bmax,2)]))
  od;
  t
end proc:
map(f, [$1..100]); # Robert Israel, Jul 26 2024

A070114 Numbers n such that [A070080(n), A070081(n), A070082(n)] is a scalene integer triangle with prime side lengths.

Original entry on oeis.org

30, 101, 153, 193, 240, 328, 334, 392, 444, 454, 519, 544, 603, 621, 771, 777, 795, 799, 878, 911, 1005, 1123, 1135, 1262, 1508, 1526, 1538, 1568, 1694, 1818, 1848, 1858, 1999, 2023, 2037, 2066, 2193, 2223, 2253, 2454

Offset: 1

Reinhard Zumkeller, May 05 2002

nonn

			a(2)=101: [A070080(101), A070081(101), A070082(101)]=[5<7<11].

R. Zumkeller, Integer-sided triangles

Cf. A070090, A070123, A070132, A070112, A070111.

A070129 Numbers n such that [A070080(n), A070081(n), A070082(n)] is an obtuse integer triangle with prime side lengths.

Original entry on oeis.org

5, 14, 30, 101, 133, 153, 163, 193, 328, 334, 392, 444, 454, 472, 519, 542, 603, 621, 714, 771, 777, 795, 878, 907, 1005, 1123, 1135, 1508, 1526, 1538, 1694, 1818, 1848, 1858, 1888, 1999, 2023, 2037, 2064, 2066, 2193

Offset: 1

Reinhard Zumkeller, May 05 2002

nonn

			a(3)=30: [A070080(30), A070081(30), A070082(30)]=[3,5,7], A070085(30)=3^2+5^2-7^2=9+25-49=-15>0.

R. Zumkeller, Integer-sided triangles

Cf. A070103, A070132, A070135, A070111, A070127.

A070130 Numbers n such that [A070080(n), A070081(n), A070082(n)] is an obtuse scalene integer triangle.

Original entry on oeis.org

8, 13, 20, 21, 25, 29, 30, 36, 37, 41, 42, 44, 49, 50, 56, 57, 59, 62, 66, 67, 69, 74, 75, 77, 78, 79, 80, 86, 87, 89, 96, 97, 99, 100, 101, 102, 105, 110, 111, 113, 115, 122, 123, 125, 126, 127, 128, 130, 131, 138, 139, 141, 143

Offset: 1

Reinhard Zumkeller, May 05 2002

nonn

			a(20)=67: [A070080(67), A070081(67), A070082(67)]=[4<7<9], A070085(67)=4^2+7^2-9^2=16+49-81=-16<0.

R. Zumkeller, Integer-sided triangles

Cf. A024156, A070132, A070131, A070112, A070130.

cp's OEIS Frontend

A070127 Numbers n such that [A070080(n), A070081(n), A070082(n)] is an obtuse integer triangle.

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A070112 Numbers n such that [A070080(n), A070081(n), A070082(n)] is a scalene integer triangle.

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A070111 Numbers k such that [A070080(k), A070081(k), A070082(k)] is an integer triangle with prime sides.

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Extensions

A070105 Number of integer triangles with perimeter n and prime side lengths which are obtuse and scalene.

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Maple

A070114 Numbers n such that [A070080(n), A070081(n), A070082(n)] is a scalene integer triangle with prime side lengths.

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A070129 Numbers n such that [A070080(n), A070081(n), A070082(n)] is an obtuse integer triangle with prime side lengths.

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A070130 Numbers n such that [A070080(n), A070081(n), A070082(n)] is an obtuse scalene integer triangle.

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