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(0=0, 1=1, 2=2, 3=3, 4=2^2, 5=5, 6=2*3, 7=7, 8=2^3, 9=3^2, 10=2*5, 11=11, 12=2^2*3, ...) becomes (0*0*1, 1*2*2, 3*3*4, 2*2*5, 5*6*2, 3*7*7, 8*2*3, 9*3*2, 10*2*5, 11*11*12, 2*2*3, ...).
1

%I #8 Oct 05 2015 02:57:11

%S 0,4,36,20,60,147,48,54,100,1452,12,2366,210,240,136,612,114,760,210,

%T 462,506,1104,225,260,702,252,28,25230,30,30752,330,1122,1190,1260,12,

%U 2738,1444,1521,240,8405,252,12943,176,1485,460,2162,4512,588,700,20

%N (0=0, 1=1, 2=2, 3=3, 4=2^2, 5=5, 6=2*3, 7=7, 8=2^3, 9=3^2, 10=2*5, 11=11, 12=2^2*3, ...) becomes (0*0*1, 1*2*2, 3*3*4, 2*2*5, 5*6*2, 3*7*7, 8*2*3, 9*3*2, 10*2*5, 11*11*12, 2*2*3, ...).

%e 2*2*3 = 12 = a(11),

%e 13*13*14 = 2366 = a(12),

%e 2*7*15 = 210 = a(13),

%e 3*5*16 = 240 = a(14),

%e 2*4*17 = 136 = a(15),

%e 17*18*2 = 612 = a(16),

%e 3*2*19 = 114 = a(17),

%e etc.

%p pflat2 := proc(nmax) local a, ifs, n, p, c ; a := [0,0,1,1] ; for n from 2 to nmax do ifs := ifactors(n)[2] ; a := [op(a),n] ; for p in ifs do # a := [op(a), op(1, p)] ; a := [op(a),op(1, p)] ; if op(2, p) > 1 then a := [op(a), op(2, p)] ; fi; od: od: a ; end proc: pL := pflat2(100) ; for n from 1 to nops(pL)-3 by 3 do printf("%d,", op(n, pL)*op(n+1, pL)*op(n+2,pL) ) ; od: # _R. J. Mathar_, Apr 14 2010

%Y Cf. A002808, A136740, A136811, A143716.

%K nonn

%O 1,2

%A _Juri-Stepan Gerasimov_, Nov 17 2008

%E Terms from a(18) on replaced by _R. J. Mathar_, Apr 14 2010