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A306105 Numbers with digits in {0,1,2} such that every other digit is strictly less than its neighbors. 7
0, 1, 2, 10, 20, 21, 101, 102, 201, 202, 212, 1010, 1020, 1021, 2010, 2020, 2021, 2120, 2121, 10101, 10102, 10201, 10202, 10212, 20101, 20102, 20201, 20202, 20212, 21201, 21202, 21212, 101010, 101020, 101021, 102010, 102020, 102021, 102120, 102121 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Terms of A032858 written in base 3.

There are A000045(n+2) terms with n digits (where 0 is taken to have no digits), so the first term with n digits is at index A000071(n+3). See A032858 for the proof.

LINKS

Table of n, a(n) for n=1..40.

FORMULA

a(n) = A007089(A032858(n)).

PROG

(PARI) {A=[0, 1, 2]; F=[1, 1]; for(n=0, 4, F=[F[2], vecsum(F)]; for(k=1, 3, T=max(k*10, 21)*10^n; A=concat(A, apply(t->t+T, A[F[2]-1+if(k>2, F*[2, -1]~)..vecsum(F)-2])))); A}

CROSSREFS

Cf. A306106 .. A306111 and A297147: analog for bases 3..9 and 10.

Cf. A000045 (Fibonacci), A000071(n) = Sum(k=0..n-2,A45(k)) = A000045(n)-1.

Cf. A032858 and A032859 .. A032865 for other bases 3..10.

Sequence in context: A259096 A317859 A009342 * A038103 A307254 A293725

Adjacent sequences:  A306102 A306103 A306104 * A306106 A306107 A306108

KEYWORD

nonn,base

AUTHOR

M. F. Hasler, Oct 05 2018

STATUS

approved

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Last modified May 21 22:24 EDT 2019. Contains 323467 sequences. (Running on oeis4.)