A143852 (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,..)).

6, 8, 1, 16, 16, 13, 21, 20, 13, 34, 7, 17, 36, 37, 17, 27, 5, 13, 3, 29, 28, 6, 30, 8, 17, 66, 9, 1, 47, 52, 89, 8, 14, 77, 41, 81, 6, 31, 1, 1, 91, 8, 124, 13, 31, 13, 82, 17, 55, 69, 103, 10, 13, 100, 119, 18, 155, 6, 91, 40, 111, 11, 32, 55, 9, 10, 15, 37, 10, 115, 23, 124, 17

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

Abs (2-7-3-5)=abs (-13) =13=a(6).
Abs (2-4-17-2)=abs(-21)=21=a(7).
Abs (3-2-19-2)=abs (-20)=20=a(8).
Abs (2-5-3-7)=abs (-13)=13=a(9).
Abs (2-11-23-2)=abs(-34)=34=a(10),
etc.

Maple

g:= proc(n) local F;
   F:= sort(ifactors(n)[2], (a, b) -> a[1]<b[1]);
   op(subs(1=NULL, map(op, F)));
end proc:
g(1):= 1:
L:= map(g, [$1..300]):
seq(abs(L[i]-L[i+1]-L[i+2]-L[i+3]), i=1..nops(L)-3, 4); # Robert Israel, Apr 25 2016

Mathematica

Abs@ Total@ MapAt[Abs, Minus@ #, {1}] & /@ Partition[#, 4] &@ Flatten[FactorInteger /@ Range@ 134 /. {a_, b_} /; b == 1 :> {a}] (* Michael De Vlieger, Apr 25 2016 *)

Crossrefs

Cf. A141287, A141261, A136678, A143717.

Sequence in context: A198549 A019852 A326770 * A372311 A246844 A246845

Adjacent sequences: A143849 A143850 A143851 * A143853 A143854 A143855

Keyword

nonn

Author

Juri-Stepan Gerasimov, Nov 17 2008

Extensions

Corrected (10 replaced by 8) and extended by R. J. Mathar, Apr 18 2010

Status

approved