cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-8 of 8 results.

A071157 The zero-free, right-to-left factorial walk encoding for each rooted plane tree encoded by A014486. Sequence A071155 shown with factorial expansion (A007623).

Original entry on oeis.org

0, 1, 11, 21, 111, 211, 121, 221, 321, 1111, 2111, 1211, 2211, 3211, 1121, 2121, 1221, 2221, 3221, 1321, 2321, 3321, 4321, 11111, 21111, 12111, 22111, 32111, 11211, 21211, 12211, 22211, 32211, 13211, 23211, 33211, 43211, 11121, 21121, 12121
Offset: 0

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Author

Antti Karttunen, May 14 2002

Keywords

Comments

Apart from the initial term (0, which encodes the null tree), if we scan the digits from the right (the least significant digit which is always 1) to the left (the most significant), then each successive digit to the left is at most one greater than the previous and never less than one.
Note: this finite decimal representation works only up to the 23712nd term, as the 23713rd such walk is already (10,9,8,7,6,5,4,3,2,1). The sequence A071158 shows the initial portion of this sequence sorted.

Crossrefs

Corresponding Łukasiewicz words: A071153.
Essentially the same as A071159 but with digits reversed.

Formula

a(n) = A007623(A071155(n)).

A085200 Inverse function of N -> N injection A071155.

Original entry on oeis.org

0, 1, 0, 2, 0, 3, 0, 0, 0, 4, 0, 6, 0, 0, 0, 5, 0, 7, 0, 0, 0, 0, 0, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 9, 0, 14, 0, 0, 0, 11, 0, 16, 0, 0, 0, 0, 0, 19, 0, 0, 0, 0, 0, 0, 0, 0, 0, 10, 0, 15, 0, 0, 0, 12, 0, 17, 0, 0, 0, 0, 0, 20, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 13, 0, 18, 0, 0, 0, 0, 0, 21, 0, 0, 0
Offset: 0

Views

Author

Antti Karttunen, Jun 23 2003

Keywords

Comments

a(0)=0 because A071155(0)=0, but a(n) = 0 also for those n which do not occur as values of A071155. All positive natural numbers occur here once.

Crossrefs

a(A071155(n)) = n for all n. Cf. A080300.

A071153 Łukasiewicz word for each rooted plane tree (interpretation e in Stanley's exercise 19) encoded by A014486 (or A063171), with the last leaf implicit, i.e., these words are given without the last trailing zero, except for the null tree which is encoded as 0.

Original entry on oeis.org

0, 1, 20, 11, 300, 201, 210, 120, 111, 4000, 3001, 3010, 2020, 2011, 3100, 2101, 2200, 1300, 1201, 2110, 1210, 1120, 1111, 50000, 40001, 40010, 30020, 30011, 40100, 30101, 30200, 20300, 20201, 30110, 20210, 20120, 20111, 41000, 31001, 31010
Offset: 0

Views

Author

Antti Karttunen, May 14 2002

Keywords

Comments

Note: this finite decimal representation works only up to the 6917th term, as the 6918th such word is already (10,0,0,0,0,0,0,0,0,0). The sequence A071154 shows the initial portion of this sequence sorted.

Examples

			The 11th term of A063171 is 10110010, corresponding to parenthesization ()(())(), thus its Łukasiewicz word is 3010. The 18th term of A063171 is 11011000, corresponding to parenthesization (()(())), thus its Łukasiewicz word is 1201. I.e., in the latter example there is one list on the top-level, which in turn contains two sublists, of which the first is zero elements long and the second is a sublist containing one empty sublist (the last zero is omitted).
		

Crossrefs

For n >= 1, the number of zeros in the term a(n) is given by A057514(n)-1.
The first digit of each term is given by A057515.
Corresponding factorial walk encoding: A071155 (A071157, A071159).
a(n) = A079436(n)/10.

A071156 Apart from the initial term (0), lists all integers whose factorial expansion ends with 1 (i.e., are odd numbers), do not contain a digit zero and each successive digit to the left is at most one greater than the preceding digit.

Original entry on oeis.org

0, 1, 3, 5, 9, 11, 15, 17, 23, 33, 35, 39, 41, 47, 57, 59, 63, 65, 71, 87, 89, 95, 119, 153, 155, 159, 161, 167, 177, 179, 183, 185, 191, 207, 209, 215, 239, 273, 275, 279, 281, 287, 297, 299, 303, 305, 311, 327, 329, 335, 359, 417, 419, 423, 425, 431, 447, 449
Offset: 0

Views

Author

Antti Karttunen, May 14 2002

Keywords

Comments

a(n) = A085198(A014486(n)) = A071155(A057164(n)). Catalan numbers A000108(n) gives the number of terms whose factorial expansion contain n digits.
0 is included by considering it to have the empty string as its factorial base representation. - Franklin T. Adams-Watters, Jun 28 2006

Crossrefs

The beginning of this sequence expanded in the factorial number system: A071158. Inverse function: A085199. First differences: A085191.
Cf. A000108 (row lengths), A071155, A120696.

A085201 Array A(x,y): Position of the concatenation of binary strings A014486(x) & A014486(y) in A014486, listed antidiagonalwise as A(0,0), A(1,0), A(0,1), A(2,0), A(1,1), A(0,2), ...

Original entry on oeis.org

0, 1, 1, 2, 2, 2, 3, 4, 4, 3, 4, 6, 9, 5, 4, 5, 9, 14, 10, 9, 5, 6, 11, 23, 15, 23, 10, 6, 7, 14, 28, 24, 37, 24, 11, 7, 8, 16, 37, 29, 65, 38, 25, 12, 8, 9, 19, 42, 38, 79, 66, 39, 26, 13, 9, 10, 23, 51, 43, 107, 80, 67, 40, 27, 23, 10, 11, 25, 65, 52, 121, 108, 81, 68, 41, 65, 24, 11
Offset: 0

Views

Author

Antti Karttunen, Jun 23 2003

Keywords

Comments

This table is induced by the 2-ary form of the list-function 'append' present in the programming languages like Lisp, Scheme and Prolog.

Crossrefs

Transpose: A085202. Variant: A085203. Row 1: A085223, Column 1: A072795.

Formula

a(0, y)=y, a(x, y) = A072764bi(A072771(x), a(A072772(x), y))
a(x, y) = A080300(A085207bi(A014486(x), A014486(y))) = A085200(A085215bi(A071155(y), A071155(x)))

A085203 Array A(x,y): Position of the totally balanced binary string obtained by concatenating the binary strings A014486(x) & A014486(y) in such a way that the latter is inserted after the least significant 1-bit of the former, followed by the remaining 0-bits, if any. Listed antidiagonalwise as A(0,0), A(1,0), A(0,1), A(2,0), A(1,1), A(0,2), ...

Original entry on oeis.org

0, 1, 1, 2, 3, 2, 3, 5, 7, 3, 4, 8, 12, 8, 4, 5, 10, 21, 13, 17, 5, 6, 13, 26, 22, 31, 18, 6, 7, 15, 35, 27, 58, 32, 20, 7, 8, 18, 40, 36, 73, 59, 34, 21, 8, 9, 22, 49, 41, 100, 74, 62, 35, 22, 9, 10, 24, 63, 50, 115, 101, 76, 63, 36, 45, 10, 11, 27, 68, 64, 142, 116, 104, 77, 64, 87, 46
Offset: 0

Views

Author

Antti Karttunen, Jun 23 2003

Keywords

Comments

This table is induced by the list-function 'app-to-xrt' whose Scheme-definition is given below, in the same way as A085201 is induced by the ordinary 'append'-function.

Crossrefs

Transpose: A085204. Variant: A085201. Row 1: A085225, Column 1: A057548.

Formula

a(0, y) = y, a(x, y) = A057548(a(A072771(x), y)) if A072772(x)=0, otherwise A072764bi(A072771(x), a(A072772(x), y)).
a(x, y) = A080300(A085211bi(A014486(x), A014486(y))) = A085200(A085219bi(A071155(y), A071155(x))).

A236855 a(n) is the sum of digits in A239903(n).

Original entry on oeis.org

0, 1, 1, 2, 3, 1, 2, 2, 3, 4, 3, 4, 5, 6, 1, 2, 2, 3, 4, 2, 3, 3, 4, 5, 4, 5, 6, 7, 3, 4, 4, 5, 6, 5, 6, 7, 8, 6, 7, 8, 9, 10, 1, 2, 2, 3, 4, 2, 3, 3, 4, 5, 4, 5, 6, 7, 2, 3, 3, 4, 5, 3, 4, 4, 5, 6, 5, 6, 7, 8, 4, 5, 5, 6, 7, 6, 7, 8, 9, 7, 8, 9, 10, 11, 3, 4
Offset: 0

Views

Author

Antti Karttunen, Apr 18 2014

Keywords

Examples

			As the 0th Catalan String is empty, indicated by A239903(0)=0, a(0)=0.
As the 18th Catalan String is [1,0,1,2] (A239903(18)=1012), a(18) = 1+0+1+2 = 4.
Note that although the range of validity of A239903 is inherently limited by the decimal representation employed, it doesn't matter here: We have a(58785) = 55, as the corresponding 58785th Catalan String is [1,2,3,4,5,6,7,8,9,10], even though A239903 cannot represent that unambiguously.
		

Crossrefs

Programs

  • Mathematica
    A236855list[m_] := With[{r = 2*Range[2, m]-1}, Reverse[Map[Total[r-#] &, Select[Subsets[Range[2, 2*m-1], {m-1}], Min[r-#] >= 0 &]]]];
    A236855list[6] (* Generates C(6) terms *) (* Paolo Xausa, Feb 19 2024 *)
  • Scheme
    (define (A236855 n) (apply + (A239903raw n)))
    (define (A239903raw n) (if (zero? n) (list) (let loop ((n n) (row (- (A081288 n) 1)) (col (- (A081288 n) 2)) (srow (- (A081288 n) 2)) (catstring (list 0))) (cond ((or (zero? row) (negative? col)) (reverse! (cdr catstring))) ((> (A009766tr row col) n) (loop n srow (- col 1) (- srow 1) (cons 0 catstring))) (else (loop (- n (A009766tr row col)) (+ row 1) col srow (cons (+ 1 (car catstring)) (cdr catstring))))))))
    ;; Alternative definition:
    (define (A236855 n) (let ((x (A071155 (A081291 n)))) (- (A034968 x) (A060130 x))))

Formula

a(n) = A034968(x) - A060130(x), where x = A071155(A081291(n)).
For up to n = A000108(11)-2 = 58784, a(n) = A007953(A239903(n)).
Catalan numbers, A000108, give the positions of ones, and the n-th triangular number occurs for the first time at the position immediately before that, i.e., a(A001453(n)) = A000217(n-1).
For each n, a(n) >= A000217(A236859(n)).

A120695 Set partitions reversed interpreted as factorial base numbers.

Original entry on oeis.org

0, 1, 3, 5, 9, 15, 11, 17, 23, 33, 57, 39, 63, 87, 35, 59, 83, 41, 65, 89, 47, 71, 95, 119, 153, 273, 177, 297, 417, 159, 279, 399, 183, 303, 423, 207, 327, 447, 567, 155, 275, 395, 179, 299, 419, 203, 323, 443, 563, 161, 281, 401, 185, 305, 425, 209, 329, 449
Offset: 0

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Author

Keywords

Examples

			The third set partition is {1,2}, 21 in base factorial is 5, so a(3) = 5.
Triangle begins:
   0;
   1;
   3,  5;
   9, 15, 11, 17, 23;
  33, 57, 39, 63, 87, 35, 59, 83, 41, 65, 89, 47, 71, 95, 119;
		

Crossrefs

Cf. A000110 (row lengths), A120698, A120696 (sorted), A120697, A071155.
Column k=0 gives A007489.

Programs

  • Maple
    b:= proc(n, m, t) option remember; `if`(n=0, [0], [seq(map(
           x-> x+j*t!, b(n-1, max(m, j), t+1))[], j=1..m+1)])
        end:
    T:= n-> b(n, 0, 1)[]:
    seq(T(n), n=0..5);  # Alois P. Heinz, Apr 04 2016
Showing 1-8 of 8 results.