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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A137409 Numbers that cannot be the value of 'C' in a primitive Pythagorean triple (A < B; A^2 + B^2 = C^2). 6
1, 2, 3, 4, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 18, 19, 20, 21, 22, 23, 24, 26, 27, 28, 30, 31, 32, 33, 34, 35, 36, 38, 39, 40, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 54, 55, 56, 57, 58, 59, 60, 62, 63, 64, 66, 67, 68, 69, 70, 71, 72, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Complement of A008846. - R. J. Mathar, Aug 15 2010

A024362(a(n)) = 0. - Reinhard Zumkeller, Dec 02 2012

Except for the 1st term 1, complement of A004613. - Federico Provvedi, Jan 26 2019

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

EXAMPLE

3,4,5; number 5 is not in this sequence.

5,12,13; number 13 is not in this sequence.

8,15,17; number 17 is not in this sequence.

7,24,25; number 25 is not in this sequence.

MATHEMATICA

okQ[1] = True;

okQ[n_] := AnyTrue[FactorInteger[n][[All, 1]], Mod[#, 4] != 1&];

Select[Range[100], okQ] (* Jean-Fran├žois Alcover, Mar 10 2019, after Federico Provvedi's comment *)

PROG

(Haskell)

import Data.List (elemIndices)

a137409 n = a137409_list !! (n-1)

a137409_list = map (+ 1) $ elemIndices 0 a024362_list

-- Reinhard Zumkeller, Dec 02 2012

CROSSREFS

Cf. A137407, A020882.

Sequence in context: A035058 A004776 A187945 * A037041 A048263 A141451

Adjacent sequences:  A137406 A137407 A137408 * A137410 A137411 A137412

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, Apr 14 2008

EXTENSIONS

Extended by R. J. Mathar, Aug 15 2010

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 October 20 20:13 EDT 2019. Contains 328272 sequences. (Running on oeis4.)