login
This site is supported by donations to The OEIS Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A101439 Areas of primitive Pythagorean triangles which are palindromes. 1
6, 63336, 474474, 666666, 4383834, 43177134, 460962269064, 60471399317406, 60490233209406, 643869171968346, 6708875775788076, 44703479297430744, 608857707707758806, 44523865177156832544, 683665820959028566386 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Other parts of the n-th triangle are {m,n},{a,b,c}:

a(1): {1,2},{3,4,5};

a(2): {8,21},{377,336,505};

a(3): {1,78},{6083,156,6085};

a(4): {26,37},{693,1924,2045};

a(5): {49,62},{1443,6076,6245};

a(6): {11,158},{24843,3476,25085};

a(7): {2376,2393},{81073,11371536,11371825};

a(8): {4569,4858},{2724403,44392404,44475925};

a(9): {2974,3773},{5390853,22441804,23080205};

a(10): {5402,6829},{17453637,73780516,75816845};

a(11): {121,38132},{1454034783,9227944,1454064065};

a(12): {28407,29336},{53643247,1666695504,1667558545};

a(13): {16593,35986},{1019664547,1194231396,1570319845};

a(14): {3168,241339},{58234476697,1529123904,58254549145};

a(15): {160034,213573},{20002545173,68357882964,71224307485}.

LINKS

Table of n, a(n) for n=1..15.

EXAMPLE

666666 is a member as it is a palindromic number and is the area of a primitive Pythagorean triangle with legs a=693 & b=1924 and hypotenuse c=2045.

MATHEMATICA

lst = {}; Do[ If[ GCD[m, n] == 1, a = IntegerDigits[m*n^3 - n*m^3]; If[ Reverse[a] == a, lst = Sort[ AppendTo[ lst, a]]; Print[{n^2 - m^2, 2m*n, n^2 + m^2, m*n^3 - n*m^3}]]], {n, 55000}, {m, If[ EvenQ[n], 1, 2], n - 1, 2}]; lst (* Robert G. Wilson v, Jan 25 2005 *)

CROSSREFS

Cf. A101450.

Sequence in context: A259162 A076913 A101450 * A099112 A172750 A086897

Adjacent sequences:  A101436 A101437 A101438 * A101440 A101441 A101442

KEYWORD

nonn,base

AUTHOR

Zak Seidov, Jan 18 2005

EXTENSIONS

a(8) & a(10) - a(13) from Robert G. Wilson v, Jan 25 2005

a(14) and a(15) from Ray Chandler, Feb 10 2013

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified December 5 10:45 EST 2019. Contains 329751 sequences. (Running on oeis4.)