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Number of terms in the "comma sum" sequence (cf. A230288) starting with n, or 0 if it is infinite.
3

%I #11 Nov 04 2024 09:30:45

%S 2,1,1,1,1,122,121,121,120,120,122,121,121,120,120,120,120,119,118,

%T 119,120,120,119,118,119,118,118,117,117,117,118,118,117,117,117,117,

%U 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

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

%C 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.

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

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

%o (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.

%o (Python) # uses A230288gen() in A230288

%o def a(n): return len(list(A230288gen(start=[n])))

%o print([a(n) for n in range(100)]) # _Michael S. Branicky_, Nov 03 2024

%Y Cf. A230288, A230450, A230452.

%K nonn,base,changed

%O 0,1

%A _M. F. Hasler_, Oct 19 2013