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

 

Logo

Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A080511 Triangle whose n-th row contains the least set (ordered lexicographically) of n distinct positive integers whose arithmetic mean is an integer. 4
1, 1, 3, 1, 2, 3, 1, 2, 3, 6, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 9, 1, 2, 3, 4, 5, 6, 7, 1, 2, 3, 4, 5, 6, 7, 12, 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 15, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 18, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 21 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

The n-th row is {1,2,...,n-1,x}, where x=n if n is odd, x=3n/2 if n is even.

LINKS

Table of n, a(n) for n=1..105.

EXAMPLE

Triangle starts:

1;

1, 3;

1, 2, 3;

1, 2, 3, 6;

1, 2, 3, 4, 5;

1, 2, 3, 4, 5, 9;

1, 2, 3, 4, 5, 6, 7;

1, 2, 3, 4, 5, 6, 7, 12;

...

MAPLE

T:= proc(n) $1..n-1, `if`(irem(n, 2)=1, n, 3*n/2) end:

seq(T(n), n=1..20);  # Alois P. Heinz, Aug 29 2013

MATHEMATICA

row[n_] := Append[Range[n - 1], If[OddQ[n], n, 3 n/2]];

Table[row[n], {n, 1, 20}] // Flatten (* Jean-Fran├žois Alcover, May 21 2016 *)

CROSSREFS

Cf. A080512, A008619, A080504, A080508.

Sequence in context: A167373 A079722 A079723 * A132399 A287616 A081485

Adjacent sequences:  A080508 A080509 A080510 * A080512 A080513 A080514

KEYWORD

nonn,tabl

AUTHOR

Amarnath Murthy, Mar 20 2003

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified November 23 20:23 EST 2017. Contains 295141 sequences.