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A144158
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(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, 13=13, ..) becomes (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*13*13, ..).
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0
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2, 18, 16, 150, 42, 112, 81, 40, 605, 48, 507, 196, 225, 128, 5202, 12, 7220, 20, 441, 484, 12696, 18, 250, 676, 243, 112, 5887, 180, 4805, 320, 1089, 1156, 1225, 144, 222, 2812, 2223, 1040, 615, 3444, 903, 3784, 990, 30, 2116, 106032, 24, 686, 500, 306
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| 3*13*13=507=a(11).
14*2*7=196=a(12).
15*3*5=225=a(13).
16*2*4=128=a(14).
17*17*18=5202=a(15).
2*3*2=12=a(16).
19*19*20=7220=a(17),
etc.
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MAPLE
| pflat := proc(nmax) local a, ifs, n, p, c ; a := [1, 1] ; for n from 2 to nmax do a := [op(a), n] ; ifs := ifactors(n)[2] ; for p in ifs do a := [op(a), op(1, p)] ; if op(2, p) > 1 then a := [op(a), op(2, p)] ; fi; od: od: a ; end: L := pflat(300) ; for n from 1 to nops(L)-3 by 3 do printf("%d, ", op(n, L)*op(n+1, L)*op(n+2, L) ) ; end do: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 29 2010]
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CROSSREFS
| Cf. A141186, A136740, A136811, A143717.
Sequence in context: A093481 A132629 A174708 * A083502 A076378 A066242
Adjacent sequences: A144155 A144156 A144157 * A144159 A144160 A144161
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KEYWORD
| nonn
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AUTHOR
| Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Nov 17 2008
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EXTENSIONS
| a(37) and terms after a(46) corrected by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Apr 29 2010
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