

A199162


a(1) = 1, a(2) = 6; for n>2, a(n) = least number > a(n1) 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
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OFFSET

1,2


COMMENTS

An Ulamtype 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 !! (n1)
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



