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A087443 Least integer of each prime signature ordered first by sum of exponents and then by least integer value. 6
1, 2, 4, 6, 8, 12, 30, 16, 24, 36, 60, 210, 32, 48, 72, 120, 180, 420, 2310, 64, 96, 144, 216, 240, 360, 840, 900, 1260, 4620, 30030, 128, 192, 288, 432, 480, 720, 1080, 1680, 1800, 2520, 6300, 9240, 13860, 60060, 510510, 256, 384, 576, 864, 960, 1296, 1440 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

A025487 in a different order.

LINKS

Alois P. Heinz, Rows n = 0..26, flattened

EXAMPLE

1;

2;

4,6;

8,12,30;

16,24,36,60,210;

32,48,72,120,180,420,2310;

64,96,144,216,240,360,840,900,1260,4620,30030;

128,192,288,432,480,720,1080,1680,1800,2520,6300,9240,13860,60060,510510;

MAPLE

b:= proc(n, i, l)

      `if`(n=0, [mul(ithprime(t)^l[t], t=1..nops(l))],

      `if`(i=1, b(0, 0, [l[], 1$n]), [b(n, i-1, l)[],

      `if`(i>n, [], b(n-i, i, [l[], i]))[]]))

    end:

T:= n-> sort(b(n$2, []))[]:

seq(T(n), n=0..10);  # Alois P. Heinz, Jun 13 2012

MATHEMATICA

b[n_, i_, l_] := b[n, i, l] = If[n == 0, Join[{Product[Prime[t]^l[[t]], {t, 1, Length[l]}]}], If[i == 1, b[0, 0, Join[l, Table[1, {n}]]], Join[b[n, i - 1, l], If[i > n, {}, b[n - i, i, Append[l, i]]]]]];

T[n_] := Sort[b[n, n, {}]];

Table[T[n], {n, 0, 10}] // Flatten (* Jean-Fran├žois Alcover, Apr 06 2017, after Alois P. Heinz *)

CROSSREFS

Cf. A025487, A036035, A059901, A063008, A077569, A074140 (row sums).

Sequence in context: A131885 A173941 A194406 * A036035 A063008 A059901

Adjacent sequences:  A087440 A087441 A087442 * A087444 A087445 A087446

KEYWORD

nonn,tabf

AUTHOR

Ray Chandler, Sep 04 2003

STATUS

approved

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Last modified February 20 18:57 EST 2018. Contains 299381 sequences. (Running on oeis4.)