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Row sums of irregular triangle A070168.
5

%I #17 May 09 2021 11:18:50

%S 1,3,23,7,20,29,124,15,147,30,117,41,63,138,296,31,106,165,231,50,84,

%T 139,281,65,294,89,40616,166,212,326,40486,63,377,140,258,201,259,269,

%U 986,90,40589,126,588,183,253,327,40455,113,382,344,514,141,223,40670,41000,222

%N Row sums of irregular triangle A070168.

%C a(n) is the sum of numbers in trajectory of Terras-modified Collatz problem with first number n.

%H Indranil Ghosh, <a href="/A285098/b285098.txt">Table of n, a(n) for n = 1..10000</a>

%e The 5th row of irregular triangle A070168 is [5, 8, 4, 2, 1] whose sum is 20. a(5) = 5 + 8 + 4 + 2 + 1 = 20.

%t a[n_]:=If[n<2, 1, If[OddQ[n], (3n + 1)/2, n/2]]; Table[-1 + Plus @@ FixedPointList[a, n], {n, 100}]

%o (Python)

%o def a(n):

%o if n==1: return 1

%o l=[n]

%o while True:

%o if n%2==0: n//=2

%o else: n = (3*n + 1)//2

%o l.append(n)

%o if n<2: break

%o return sum(l)

%o print([a(n) for n in range(1, 101)])

%Y Cf. A033493, A070168.

%K nonn

%O 1,2

%A _Indranil Ghosh_, Apr 17 2017