cp's OEIS Frontend

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,..)).

%I A143852 #10 Apr 26 2016 00:15:17
%S A143852 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,
%T A143852 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,
%U A143852 103,10,13,100,119,18,155,6,91,40,111,11,32,55,9,10,15,37,10,115,23,124,17
%N 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,..)).
%H A143852 Robert Israel, <a href="/A143852/b143852.txt">Table of n, a(n) for n = 1..10000</a>
%e A143852 Abs (2-7-3-5)=abs (-13) =13=a(6).
%e A143852 Abs (2-4-17-2)=abs(-21)=21=a(7).
%e A143852 Abs (3-2-19-2)=abs (-20)=20=a(8).
%e A143852 Abs (2-5-3-7)=abs (-13)=13=a(9).
%e A143852 Abs (2-11-23-2)=abs(-34)=34=a(10),
%e A143852 etc.
%p A143852 g:= proc(n) local F;
%p A143852    F:= sort(ifactors(n)[2], (a,b) -> a[1]<b[1]);
%p A143852    op(subs(1=NULL,map(op,F)));
%p A143852 end proc:
%p A143852 g(1):= 1:
%p A143852 L:= map(g, [$1..300]):
%p A143852 seq(abs(L[i]-L[i+1]-L[i+2]-L[i+3]),i=1..nops(L)-3,4); # _Robert Israel_, Apr 25 2016
%t A143852 Abs@ Total@ MapAt[Abs, Minus@ #, {1}] & /@ Partition[#, 4] &@ Flatten[FactorInteger /@ Range@ 134 /. {a_, b_} /; b == 1 :> {a}] (* _Michael De Vlieger_, Apr 25 2016 *)
%Y A143852 Cf. A141287, A141261, A136678, A143717.
%K A143852 nonn
%O A143852 1,1
%A A143852 _Juri-Stepan Gerasimov_, Nov 17 2008
%E A143852 Corrected (10 replaced by 8) and extended by _R. J. Mathar_, Apr 18 2010