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

 

Logo

Invitation: celebrating 50 years of OEIS, 250000 sequences, and Sloane's 75th, there will be a conference at DIMACS, Rutgers, Oct 9-10 2014.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A025582 A B_2 sequence: a(n) = least value such that sequence increases and pairwise sums of elements are all distinct. 12
0, 1, 3, 7, 12, 20, 30, 44, 65, 80, 96, 122, 147, 181, 203, 251, 289, 360, 400, 474, 564, 592, 661, 774, 821, 915, 969, 1015, 1158, 1311, 1394, 1522, 1571, 1820, 1895, 2028, 2253, 2378, 2509, 2779, 2924, 3154, 3353, 3590, 3796, 3997, 4296, 4432, 4778, 4850 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

a(n) = least value such that sequence increases and pairwise differences of distinct elements are all distinct.

REFERENCES

LiJun Zhang, Bing Li, LeeTang Cheng, Constructions of QC LDPC codes based on integer sequences, Science China Information Sciences, June 2014, Volume 57, Issue 6, pp 1-14.

LINKS

David W. Wilson, Table of n, a(n) for n = 1..1000

Index entries for B_2 sequences.

EXAMPLE

After 0, 1, a(3) cannot be 2 because 2+0 = 1+1, so a(3) = 3.

PROG

(Sage)

def A025582_build(n):

....a = [0]

....psums = set([0])

....while len(a) < n:

........a += [next(k for k in IntegerRange(a[-1]+1, infinity) if not any(i+k in psums for i in a+[k]))]

........psums.update(set(i+a[-1] for i in a))

....return a[:n]  # [D. S. McNeil, Feb 20 2011]

CROSSREFS

See A011185 for more information.

A010672 is a similar sequence, but there the pairwise sums of distinct elements are all distinct.

Sequence in context: A130050 A173256 A002049 * A029452 A034434 A243190

Adjacent sequences:  A025579 A025580 A025581 * A025583 A025584 A025585

KEYWORD

nonn,changed

AUTHOR

Dan Hoey

STATUS

approved

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

Content is available under The OEIS End-User License Agreement .

Last modified July 29 08:48 EDT 2014. Contains 245020 sequences.