login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A199162 a(1) = 1, a(2) = 6; for n>2, a(n) = least number > a(n-1) which is a unique sum of two distinct earlier terms. 2
1, 6, 7, 8, 9, 10, 11, 12, 14, 24, 26, 27, 28, 29, 31, 45, 46, 47, 48, 49, 62, 68, 82, 83, 84, 85, 98, 104, 117, 122, 135, 142, 154, 155, 159, 172, 191, 192, 193, 194, 195, 209, 234, 245, 248, 249, 250, 265, 266, 267, 268, 270, 283, 302, 303, 304, 305, 306 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

An Ulam-type sequence - see A002858 for many further references, comments, etc.

LINKS

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

Eric Weisstein's World of Mathematics, Ulam Sequence

Wikipedia, Ulam number

Index entries for Ulam numbers

EXAMPLE

13 is not a term, as 13 = 7+6 = a(3)+a(2) and 13 = 12+1 = a(8)+a(1);

14 is a term, because 14 = 8 + 6 = a(4) + a(2) is unique for distinct terms, a(9) = 14.

PROG

(Haskell)

a199162 n = a199162_list !! (n-1)

a199162_list = 1 : 6 : ulam 2 6 a199162_list

-- Function ulam as defined in A002858.

-- Reinhard Zumkeller, Nov 03 2011

CROSSREFS

Cf. A003663.

Sequence in context: A182307 A023384 A053407 * A120199 A162786 A269801

Adjacent sequences:  A199159 A199160 A199161 * A199163 A199164 A199165

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Nov 03 2011

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 08:28 EDT 2021. Contains 348099 sequences. (Running on oeis4.)