A147790 a(1) = 3, a(n) = round(a(n-1)*3/2) for n > 1, using round-to-even method.

3, 4, 6, 9, 14, 21, 32, 48, 72, 108, 162, 243, 364, 546, 819, 1228, 1842, 2763, 4144, 6216, 9324, 13986, 20979, 31468, 47202, 70803, 106204, 159306, 238959, 358438, 537657, 806486, 1209729, 1814594, 2721891, 4082836, 6124254, 9186381, 13779572

Offset

1,1

Comments

See Wikipedia link and MathWorld link for different methods of rounding half-integers.

Links

Table of n, a(n) for n=1..39.

Eric Weisstein's MathWorld, Nearest Integer Function

Wikipedia, Rounding

Example

a(2) = round(3*3/2) = 4;
a(3) = round(4*3/2) = 6;
a(4) = round(6*3/2) = 9.

Mathematica

lst={}; s=2; Do[s=Round[s*1.5]; AppendTo[lst, s], {n, 1, 5!}]; lst
NestList[Round[3 #/2]&, 3, 40] (* Harvey P. Dale, Sep 15 2011 *)

Prog

(Magma) RoundToEven:=function(n); d:=Floor(n); return n-d ne 1/2 select Round(n) else d+(d mod 2); end function; [ n eq 1 select 3 else RoundToEven(Self(n-1)*3/2): n in [1..39] ]; // Klaus Brockhaus, Nov 17 2008
(PARI) {RoundToEven(n)=local(d); d=divrem(n, 1); if(d[2]<>1/2, round(n), d[1]+d[1]%2)} {a=2; while(a<10^7, print1(a=RoundToEven(a*3/2), ", "))} \\ Klaus Brockhaus, Nov 17 2008

Crossrefs

Cf. A061418, A147788, A147789.

Sequence in context: A030712 A387137 A025000 * A048577 A107340 A326655

Adjacent sequences: A147787 A147788 A147789 * A147791 A147792 A147793

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Nov 13 2008

Extensions

Edited by Klaus Brockhaus, Nov 17 2008

Status

approved