A230453 Number of terms in the "comma sum" sequence (cf. A230288) starting with n, or 0 if it is infinite.

2, 1, 1, 1, 1, 122, 121, 121, 120, 120, 122, 121, 121, 120, 120, 120, 120, 119, 118, 119, 120, 120, 119, 118, 119, 118, 118, 117, 117, 117, 118, 118, 117, 117, 117, 117, 116, 116, 116, 116, 117, 116, 116, 116, 116, 115, 115, 4, 115, 4, 115, 115, 4, 115, 4, 114, 114, 114, 114, 3, 114, 114, 114, 114, 3, 3, 113, 3, 113, 2, 3, 113, 3, 113

Offset: 0

Author

M. F. Hasler, Oct 19 2013

Keywords

• nonn
• base

Comments

A "comma sum" sequence is such that a(n+1)-a(n) = rightmost digit of a(n) + leftmost digit of a(n+1), taking usually the smallest possible solution.

The value a(0)=2 corresponds to the sequence (0,1), not to sequence A230288 starting by definition with 0,5,....

a(n)>0 for all n<396. See A230450 for the sequence starting with 396.

Crossrefs

Cf. A230288, A230450, A230452.

Programs

PARI

for(n=0,196,print1(#A230288_list([n],150),",")) \\ The second argument (nMax) is useful only for n>= 396. If this value (here 150) is printed, this most probably means that the sequence is infinite, a(n)=0.

Python

# uses A230288gen() in A230288
def a(n): return len(list(A230288gen(start=[n])))
print([a(n) for n in range(100)]) # Michael S. Branicky, Nov 03 2024