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!)
A117931 Inductive sum-and-difference sequence. 2
1, 2, 7, 5, 9, 3, 10, 4, 14, 6, 19, 8, 23, 11, 25, 12, 28, 13, 31, 15, 33, 16, 35, 17, 38, 18, 41, 20, 43, 21, 46, 22, 50, 24, 53, 26, 56, 27, 59, 29, 62, 30, 66, 32, 70, 34, 73, 36, 76, 37, 79, 39, 82, 40, 86, 42, 89, 44, 92, 45, 95, 47, 97, 48, 100, 49, 103, 51, 106, 52, 109 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

A permutation of the natural numbers.

LINKS

Table of n, a(n) for n=1..71.

FORMULA

a(1)=1, a(2)=2 and for n>=3 let F(n)={a(1),a(2),...,a(n)}. For odd n>=3, a(n)=x+y where x,y are the least positive integers not in F(n-1); for even n>=3, a(n)=least positive difference x-y such that x,y are in F(n-1) and x-y is not in F(n-1).

EXAMPLE

a(3)=3+4, a(4)=7-2, a(4)=3+6, a(5)=5-2, a(6)=4+6.

CROSSREFS

Cf. A117932, A117933.

Sequence in context: A198737 A010593 A332322 * A011051 A024691 A220606

Adjacent sequences:  A117928 A117929 A117930 * A117932 A117933 A117934

KEYWORD

nonn

AUTHOR

Clark Kimberling, Apr 03 2006

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 March 5 11:27 EST 2021. Contains 341823 sequences. (Running on oeis4.)