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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A227097 a(n) = n successive applications of the <*>(3,2) operator to 1. 1
 1, 3, 9, 27, 61, 123, 349, 1007, 2021, 4043, 8089, 16187, 42481, 125363, 271029, 612067, 1234141, 3498383, 10087069, 20254147, 40558401, 81167203, 163394609, 429879827, 1268830461, 2745691323, 6196472949, 12499016807, 35407044421, 101221129243, 202643278689 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS x<*>(3,2) means that the number obtained from digits of x are alternatively multiplicated by 3 and by 2 from right to left (taking carries into account). a(n) = (...(1<*>(3,2))<*>(3,2))...<*>(3,2) (n recursive applications of the <*>(3,2) operator. LINKS Alois P. Heinz, Table of n, a(n) for n = 0..1000 V. Shevelev, Partition of multiplication EXAMPLE a(0) = 1 (no operation) a(2) = 1*3 a(3) = (1*3)*3 = 9 a(4) = ((1*3)*3)*3 = 27 a(5) = (27)<*>(3,2) = [2*2,7*3] = 40 + 21 = 61 a(6) = (61)<*>(3,2) = [2*6,1*3] = 120+3 = 123 MAPLE a:= proc(n) option remember; local i, m, r; if n=0 then 1 else m, r:= a(n-1), 0; for i from 0 while m>0 do r:= r +10^i *irem(m, 10, 'm') *(3-irem(i, 2)) od; r fi end: seq(a(n), n=0..40); # Alois P. Heinz, Jul 05 2013 MATHEMATICA ShDM[n_, {a_, b_}] := Module[{ex = 0}, Plus @@ FoldList[(10^ex)*#2*{a, b}[[1 + Mod[ex++, 2]]] &, 0, Reverse@IntegerDigits[n, 10]]]; NestList[ShDM[#, {3, 2}] &, 1, 25] CROSSREFS Sequence in context: A015955 A357008 A097803 * A201202 A260938 A274626 Adjacent sequences: A227094 A227095 A227096 * A227098 A227099 A227100 KEYWORD nonn,base AUTHOR Vladimir Shevelev, Jul 01 2013 EXTENSIONS Example, Mathematica program, extension and corrected definition by Olivier Gérard, Jul 05 2013 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 29 21:40 EDT 2023. Contains 363042 sequences. (Running on oeis4.)