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A080905 Sequence of run lengths in first differences of A080900. 4
4, 1, 4, 1, 4, 1, 2, 1, 1, 1, 2, 1, 4, 1, 4, 1, 2, 1, 1, 1, 2, 1, 4, 1, 4, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 4, 1, 4, 1, 2, 1, 1, 1, 2, 1, 4, 1, 4, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 4, 1, 4, 1, 2, 1, 1, 1, 2, 1, 4, 1, 4, 1, 2, 1, 1, 1, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Even after 400000 terms there is no clear pattern here.
LINKS
EXAMPLE
A080900 begins 1, 6, 11, 16, 21, 19, 24, 29, 34, 39, 37, 42, 47, 52, 57, 55, 60, 65, ..., the differences are 5, 5, 5, 5, -2, 5, 5, 5, 5, -2, ... with runs of lengths 4, 1, 4, 1, ...
PROG
(PARI)
up_to = 20000;
A080905list(up_to_n) = { my(xs=Map(), v, d, ds=vector(up_to_n)); mapput(xs, 1, 1); v = 1; for(n=2, 1+up_to_n, v += (d=if(mapisdefined(xs, n), -2, +5)); mapput(xs, v, n); ds[n-1] = d); my(runlens=List([]), rl=1); for(i=2, #ds, if(ds[i]==ds[i-1], rl++, listput(runlens, rl); rl=1)); Vec(runlens); };
v080905 = A080905list(up_to);
A080905(n) = v080905[n]; \\ Antti Karttunen, Feb 24 2020
CROSSREFS
Sequence in context: A144865 A096622 A331291 * A010685 A174571 A099301
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Apr 01 2003
STATUS
approved

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Last modified March 29 08:59 EDT 2024. Contains 371268 sequences. (Running on oeis4.)