A141186 -id:A141186 - cp's OEIS frontend

A144122 (1, 2, 3, 2^2, 5, 23, 7, 2^3, 3^2, 25, 11, 2^23, 13, ...) becomes (0, 1, 4, 6^8, 9, 1012, 14, 15^16, 18^20, 2122, 24, 25^2627, 28, ...).

0, 1, 4, 1679616, 9, 120, 14, 6568408355712890625, 12748236216396078174437376, 462, 24, 59952043329758453182876110076904296875, 28, 960, 1122, 38587762477395204358312525169472792185842990875244140625, 38

Offset: 1

Juri-Stepan Gerasimov, Nov 17 2008

nonn

			6^8 = 1679616 = a(4),
9 = a(5),
10*12 = 120 = a(6),
etc.

Cf. A141468, A141186, A143677.

A141468 := proc(n) if n <=2 then n-1; else for a from procname(n-1)+1 do if not isprime(a) then return a; end if; end do: end if; end proc:
A144122 := proc(nmax) local a, ifs, n, p, c ; printf("0,1,") ; c := 3 ; for n from 3 to nmax do ifs := ifactors(n)[2] ; a := 1; for p in ifs do if op(2,p) > 1 then a := a*A141468(c)^A141468(c+1) ; c := c+2 ; else a := a*A141468(c) ; c := c+1 ; fi; od: printf("%d,",a) ; od: return ; end: A144122(20) ; # R. J. Mathar, Apr 28 2010

More terms from R. J. Mathar, Apr 28 2010

A144158 (1=1, 2=2, 3=3, 4=2^2, 5=5, 6=23, 7=7, 8=2^3, 9=3^2, 10=25, 11=11, 12=2^23, 13=13, ...) becomes (11*2, 233, 422, 556, 237, 782, 393, 2102, 51111, 1222, 31313, ...).

Original entry on oeis.org

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

Offset: 1

Juri-Stepan Gerasimov, Nov 17 2008

nonn

			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.

Cf. A141186, A136740, A136811, A143717.

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: # R. J. Mathar, Apr 29 2010

a(37) and terms after a(46) corrected by R. J. Mathar, Apr 29 2010

cp's OEIS Frontend

A144122 (1, 2, 3, 2^2, 5, 23, 7, 2^3, 3^2, 25, 11, 2^23, 13, ...) becomes (0, 1, 4, 6^8, 9, 1012, 14, 15^16, 18^20, 2122, 24, 25^2627, 28, ...).

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A144158 (1=1, 2=2, 3=3, 4=2^2, 5=5, 6=23, 7=7, 8=2^3, 9=3^2, 10=25, 11=11, 12=2^23, 13=13, ...) becomes (11*2, 233, 422, 556, 237, 782, 393, 2102, 51111, 1222, 31313, ...).

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cp's OEIS Frontend

A144122 (1, 2, 3, 2^2, 5, 2*3, 7, 2^3, 3^2, 2*5, 11, 2^2*3, 13, ...) becomes (0, 1, 4, 6^8, 9, 10*12, 14, 15^16, 18^20, 21*22, 24, 25^26*27, 28, ...).

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A144158 (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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A144122 (1, 2, 3, 2^2, 5, 23, 7, 2^3, 3^2, 25, 11, 2^23, 13, ...) becomes (0, 1, 4, 6^8, 9, 1012, 14, 15^16, 18^20, 2122, 24, 25^2627, 28, ...).

A144158 (1=1, 2=2, 3=3, 4=2^2, 5=5, 6=23, 7=7, 8=2^3, 9=3^2, 10=25, 11=11, 12=2^23, 13=13, ...) becomes (11*2, 233, 422, 556, 237, 782, 393, 2102, 51111, 1222, 31313, ...).