A285098 Row sums of irregular triangle A070168.

1, 3, 23, 7, 20, 29, 124, 15, 147, 30, 117, 41, 63, 138, 296, 31, 106, 165, 231, 50, 84, 139, 281, 65, 294, 89, 40616, 166, 212, 326, 40486, 63, 377, 140, 258, 201, 259, 269, 986, 90, 40589, 126, 588, 183, 253, 327, 40455, 113, 382, 344, 514, 141, 223, 40670, 41000, 222

Offset: 1

Author

Indranil Ghosh, Apr 17 2017

Keywords

• nonn

Comments

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

Examples

			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.
		

Links

• Indranil Ghosh, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A033493, A070168.

Programs

Mathematica

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

Python

def a(n):
    if n==1: return 1
    l=[n]
    while True:
        if n%2==0: n//=2
        else: n = (3*n + 1)//2
        l.append(n)
        if n<2: break
    return sum(l)
print([a(n) for n in range(1, 101)])