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A061852 Digital representation of m contains only either 1's or 2's (but not both 1's and 2's) and 0's, is palindromic and contains no singleton 2's, 1's or 0's. 3
11, 22, 111, 222, 1111, 2222, 11111, 22222, 110011, 111111, 220022, 222222, 1100011, 1111111, 2200022, 2222222, 11000011, 11100111, 11111111, 22000022, 22200222, 22222222, 110000011, 111000111, 111111111, 220000022, 222000222 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
a(n) = A008919(n)/99.
EXAMPLE
From M. F. Hasler, Oct 17 2022: (Start)
Written in rows, where each row has terms of given length and given digit set (either no 2 or no 1), the sequence starts:
row | terms
------+------------------------------------
1 | 11
2 | 22
3 | 111
4 | 222
5 | 1111
6 | 2222
7 | 11111
8 | 22222
9 | 110011, 111111
10 | 220022, 222222
Then for any n >= 1, row 2n = 2*(row 2n-1) and row 2n-1 = (terms in A061851 with n+1 digits), and the number of terms in row n is Fibonacci(ceiling(n/4)) = A000045(A002265(n+3)), and their length (number of digits) is ceiling(n/2)+1 = floor((n+3)/2). (End)
PROG
(PARI) A061852_row(n)=A061851_row(n\/2+1)*(2-n%2) \\ Note: This refers to rows as defined in EXAMPLE, while A061851_row gives the n-digit terms. - M. F. Hasler, Oct 17 2022
CROSSREFS
Cf. A008919.
Union of A061851 and twice A061851.
Number of terms with k digits is 2*Fibonacci(floor(k/2)) = 2*A000045(A004526(k)) = A006355(floor(k/2)+1).
Sequence in context: A034708 A091784 A213972 * A083511 A067894 A094620
KEYWORD
base,nonn
AUTHOR
Henry Bottomley, May 10 2001
STATUS
approved

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Last modified May 18 15:56 EDT 2024. Contains 372664 sequences. (Running on oeis4.)