A049074 Ulam's conjecture (steps to return n to 1 after division by 2 and, if needed, multiplication by 3 with 1 added).

8, 3, 49, 7, 36, 55, 288, 15, 339, 46, 259, 67, 119, 302, 694, 31, 214, 357, 519, 66, 148, 281, 633, 91, 658, 145, 101440, 330, 442, 724, 101104, 63, 841, 248, 540, 393, 535, 557, 2344, 106, 101331, 190, 1338, 325, 497, 679, 100979, 139, 806, 708, 1130, 197

Offset

1,1

Comments

Appeared in School Science and Mathematics in 1982.

Links

Table of n, a(n) for n=1..52.

Enoch Haga, Problem, School Science and Mathematics, Nov 1983, vol. 83, no 7, page 628.

LaBar, Problem #3929, School Science and Mathematics, Dec 1982, vol. 82 no 8, page 715.

Example

Beginning at n=1, algorithm produces s+t+a=8.

Prog

(This was in the formula section but is clearly a program in some language. - N. J. A. Sloane, Apr 18 2017)
n=n+1:a=n\x=n/2\if int(x)=x then e=e+1:n=x:s=s+n: if n=1 then print s+t+a:e=0:o=0:s=0:t=0:n=a:return to n=n+1\if int(x)<>x then o=o+1:y=n*3+1:n=y:t=t+n: if n=1 then print s+t+a:e=0:o=0:s=0:t=0:n=a:return to n=n+1:else return to x=n/2
(Python)
def a(n):
    if n==1: return 8
    l=[n]
    while True:
        if n%2==0: n//=2
        else: n = 3*n + 1
        l.append(n)
        if n<2: break
    return sum(l)
print([a(n) for n in range(1, 101)]) # Indranil Ghosh, Apr 14 2017

Crossrefs

Almost the same as A033493.

Cf. A049067.

Sequence in context: A287645 A182054 A302214 * A286034 A256046 A197245

Adjacent sequences: A049071 A049072 A049073 * A049075 A049076 A049077

Keyword

easy,nonn

Author

Enoch Haga

Status

approved