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A002977 a(1) = 1; subsequent terms are defined by the rule that if m is present so are 2m+1 and 3m+1.
(Formerly M2335)
+0
12
1, 3, 4, 7, 9, 10, 13, 15, 19, 21, 22, 27, 28, 31, 39, 40, 43, 45, 46, 55, 57, 58, 63, 64, 67, 79, 81, 82, 85, 87, 91, 93, 94, 111, 115, 117, 118, 121, 127, 129, 130, 135, 136, 139, 159, 163, 165, 166, 171, 172, 175, 183, 187, 189, 190, 193, 202, 223, 231, 235, 237 (list; graph; listen)
OFFSET

1,2

COMMENT

Complement of A132142: A132138(a(n)) = 1; for all terms m exists at least one x such that A132140(x)=m. - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Aug 20 2007

REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

M. L. Fredman and D. E. Knuth, Recurrence relations based on minimization, Abstract 71T-B234, Notices Amer. Math. Soc., 18 (1971), 960.

R. L. Graham, D. E. Knuth and O. Patashnik, Concrete Mathematics. Addison-Wesley, Reading, MA, 1990, p. 78.

LINKS

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

Benoit Cloitre, Illustration of initial terms

FORMULA

It seems that limit as n->infinity of log(A002977(n))/log(n) = C = 1.3.. and probably A002977(n) is asymptotic to u*n^C with u=1.0... - Benoit Cloitre (benoit7848c(AT)orange.fr), Nov 06 2002

EXAMPLE

a(10)=21=2*(3*(2*1+1)+1)+1: A132139(A132140(10))=A132139(43)=21;

a(14)=31=3*(3*(2*1+1)+1)+1=2*(2*(2*(2*1+1)+1)+1)+1: A132139(A132140(14))=A132139(52)=31 and A132139(A132140(16))=A132139(121)=31.

MATHEMATICA

Union[ Flatten[ NestList[{2# + 1, 3# + 1} &, 1, 6]]] (from Robert G. Wilson v (rgwv(AT)rgwv.com), May 11 2005)

CROSSREFS

Cf. A007448, A058361, A076291.

Sequence in context: A032726 A029739 A005098 this_sequence A024799 A039579 A115104

Adjacent sequences: A002974 A002975 A002976 this_sequence A002978 A002979 A002980

KEYWORD

easy,nonn,nice

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

EXTENSIONS

More terms from Ray Chandler (rayjchandler(AT)sbcglobal.net), Sep 06 2003

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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