login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A077477 Least positive integers not excluded by the rule that if n is present then 2n+1 and 3n+1 are not allowed. 6
1, 2, 6, 8, 9, 10, 11, 12, 14, 15, 16, 18, 20, 22, 24, 26, 27, 30, 32, 35, 36, 38, 39, 40, 42, 44, 47, 48, 50, 51, 52, 54, 56, 57, 58, 59, 60, 62, 63, 64, 66, 68, 69, 70, 72, 74, 75, 76, 78, 80, 83, 84, 86, 87, 88, 90, 92, 93, 94, 96 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

What is the limit of a(n)/n?

With 10000 terms, one gets a(n)/n -> 1.63317... - Jean-François Alcover Dec 11 2012

LINKS

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

EXAMPLE

a(5)=9 since 9 is not equal to 2*a(k)+1 nor 3*a(k)+1 for 1<=k<5; and since 9 is allowed to be present, then 19(=2*9+1) and 28(=3*9+1) are to be excluded.

MATHEMATICA

s = {1}; Do[u = Union[s, 2s + 1, 3s + 1]; c = Complement[Range[u // Last], u] // First; AppendTo[s, c], {10000}]; s (* Jean-François Alcover, Dec 11 2012 *)

PROG

(Haskell)

import Data.List (delete)

a077477 n = a077477_list !! (n-1)

a077477_list = f [1..] where

   f (x:xs) = x : f (delete (2*x + 1) $ delete (3*x + 1) xs)

-- Reinhard Zumkeller, Sep 14 2011

CROSSREFS

Cf. A002977.

Sequence in context: A003610 A201776 A206476 * A095879 A342751 A120736

Adjacent sequences:  A077474 A077475 A077476 * A077478 A077479 A077480

KEYWORD

easy,nice,nonn

AUTHOR

Paul D. Hanna, Nov 08 2002

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 January 26 21:03 EST 2022. Contains 350600 sequences. (Running on oeis4.)