

A063008


Canonical partition sequence (see A080577) encoded by prime factorization. The partition [P1+P2+P3+...] with P1>=P2>=P3>=... is encoded as 2^P1 * 3^P2 * 5^P3 *...


9



1, 2, 4, 6, 8, 12, 30, 16, 24, 36, 60, 210, 32, 48, 72, 120, 180, 420, 2310, 64, 96, 144, 240, 216, 360, 840, 900, 1260, 4620, 30030, 128, 192, 288, 480, 432, 720, 1680, 1080, 1800, 2520, 9240, 6300, 13860, 60060, 510510, 256, 384, 576, 960, 864, 1440, 3360
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OFFSET

0,2


COMMENTS

Partitions are ordered first by sum. Then all partitions of n are viewed as exponent tuples on n variables and their corresponding monomials are ordered reverse lexicographically. This gives a canonical ordering: [] [1] [2,0] [1,1] [3,0,0] [2,1,0] [1,1,1] [4,0,0,0] [3,1,0,0] [2,2,0,0] [2,1,1,0] [1,1,1,1]... Rearrangement of A025487, A036035 etc.
Or, least integer of each prime signature; resorted in accordance with the integer partitions described in A080577.  Alford Arnold, Feb 13 2008


LINKS

Table of n, a(n) for n=0..51.


EXAMPLE

The sequence begins
1
2
4,6
8,12,30
16,24,36,60,210
32,48,72,120,180,420,2310
64,96,144,240,216,360,840,900,1260,4620,30030
Partition for n=17 is [2,1,1,1], so a(17)=2^2*3*5*7=420.


MAPLE

with(combinat): A063008_row := proc(n) local e, w, r;
r := proc(L) local B, i; B := NULL;
for i from nops(L) by 1 to 1 do
B := B, L[i] od; [%] end:
w := proc(e) local i, m, p, P; m := infinity;
P := permute([seq(ithprime(i), i=1..nops(e))]);
for p in P do m := min(m, mul(p[i]^e[i], i=1..nops(e))) od end:
[seq(w(e), e = r(partition(n)))] end:
seq(print(A063008_row(i)), i=0..6);  Peter Luschny, Jan 23 2011


MATHEMATICA

row[n_] := Product[ Prime[k]^#[[k]], {k, 1, Length[#]}]& /@ IntegerPartitions[n]; Table[row[n], {n, 0, 8}] // Flatten (* JeanFrançois Alcover, Dec 10 2012 *)


CROSSREFS

Cf. A025487.
Cf. A059901, A025487.
See A080576 Maple (graded reflected lexicographic) ordering.
See A080577 Mathematica (graded reverse lexicographic) ordering.
See A036036 "Abramowitz and Stegun" (graded reflected colexicographic) ordering.
See A036037 for graded colexicographic ordering.
Sequence in context: A194406 A087443 A036035 * A059901 A136101 A187779
Adjacent sequences: A063005 A063006 A063007 * A063009 A063010 A063011


KEYWORD

nonn


AUTHOR

Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), Jul 02 2001


EXTENSIONS

Partially edited by N. J. A. Sloane, May 15, at the suggestion of R. J. Mathar
Corrected and (minor) edited by Daniel Forgues, Jan 03 2011


STATUS

approved



