A143678 ( 1, 2, 3, 2^2, 5, 2*3, 7, 2^3, 3^2, 2*5, 11, 2^2*3, 13, 2*7, 3*5,..) becomes (abs (1-2+3, 2-2+5, 2-3+7, 2-3+3, 2-2+5, 11-2+2, 3-13+2, 7-3+5,..)).

2, 5, 6, 2, 5, 11, 8, 9, 15, 1, 19, 9, 14, 2, 5, 13, 7, 30, 24, 13, 10, 7, 38, 14, 14, 34, 39, 11, 6, 26, 1, 7, 6, 17, 38, 5, 12, 23, 32, 3, 54, 30, 11, 6, 59, 17, 18, 69, 2, 69, 39, 2, 23, 12, 81, 6, 44, 3, 19, 38, 30, 76, 6, 4, 18, 76, 12, 99, 3, 12, 5, 97, 89, 12, 5, 56, 3, 104, 3, 39, 104, 11, 23, 28, 70, 8, 5, 11, 99, 31, 4, 8

Offset: 1

Author

Juri-Stepan Gerasimov, Nov 01 2008

Keywords

• nonn

Examples

			Abs(1-2+3)=abs(2)=2=a(1).
Abs(2-2+5)=abs(5)=5=a(2).
Abs(2-3+7)=abs(6)=6=a(3).
Abs(2-3+3)=abs(2)=2=a(4).
Abs(2-2+5)=abs(5)=5=a(5).
Abs(11-2+2)=abs(11)=11=a(6).
Abs(3-13+2)=abs(-8)=8=a(7).
Abs(7-3+5)=abs(9)=9=a(8), etc.
		

Crossrefs

Cf. A141257, A141261.

Programs

Maple

pflat2 := proc(nmax) local a, ifs, n, p, c ; a := [1] ; for n from 2 to nmax do 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:
pL := pflat2(300) : for n from 1 to nops(pL)-4 by 3 do printf("%d,", abs(op(n, pL)-op(n+1, pL)+op(n+2,pL)) ) ; od: # R. J. Mathar, Nov 06 2008

Extensions

Removed incompatibilities with internal OEIS format, extended R. J. Mathar, Nov 06 2008