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

1,2

Comments

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

Links

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

Example

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.

Mathematica

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

Prog

(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)])

Crossrefs

Cf. A033493, A070168.

Sequence in context: A105433 A196086 A196083 * A088605 A272816 A063562

Adjacent sequences: A285095 A285096 A285097 * A285099 A285100 A285101

Keyword

nonn

Author

Indranil Ghosh, Apr 17 2017

Status

approved