

A075329


Pair up the natural numbers as (r, s) (say) so that all natural numbers are obtained only once as r, s, s+r or sr: (1, 3), (5, 11), (7, 15), (9, 19), (12, 25), (14, 31), (18, 38), ... Sequence gives first member of each pair.


4



1, 5, 7, 9, 12, 14, 18, 21, 24, 27, 29, 33, 35, 39, 41, 43, 47, 49, 51, 54, 58, 60, 63, 66, 69, 72, 75, 77, 78, 82, 86, 88, 92, 94, 96, 99, 103, 105, 110, 112, 114, 116, 120, 123, 126, 129, 130, 135, 137, 140, 143, 146, 148, 152, 154, 158, 160, 164, 166, 169, 171, 172
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OFFSET

1,2


LINKS

Table of n, a(n) for n=1..62.


MAPLE

A075329 := proc(nmax) local r, s, n, stst, rtst ; r := [1] : s := [] : n := {1} : while nops(r) < 100 do stst := 1 ; while stst in n or ststop(1, r) in n or stst+op(1, r) in n do stst := stst +1 ; od ; s := [op(s), stst] ; n := n union {stst, ststop(1, r), stst+op(1, r)} ; rtst := 1 ; while rtst in n do rtst := rtst +1 ; od ; r := [op(r), rtst] ; n := n union {rtst} ; od : RETURN(r) ; end: A075329(100) ;  R. J. Mathar, Feb 03 2007


CROSSREFS

Cf. A075330, A075331, A075332.
Sequence in context: A029664 A188793 A184102 * A177031 A159018 A005427
Adjacent sequences: A075326 A075327 A075328 * A075330 A075331 A075332


KEYWORD

nonn


AUTHOR

Amarnath Murthy, Sep 18 2002


EXTENSIONS

More terms from R. J. Mathar, Feb 03 2007


STATUS

approved



