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.

Previous Showing 11-19 of 19 results.

A262890 a(n) = total number of nodes in the finite subtrees branching from node n in the infinite trunk (A259934) of the tree generated by edge-relation A049820(child) = parent.

Original entry on oeis.org

6, 0, 41, 0, 0, 5, 0, 16, 0, 2, 0, 1, 1, 26, 4, 0, 0, 3, 0, 1, 13, 0, 105, 2, 1, 1, 2, 5, 18, 7, 0, 0, 0, 1, 3, 3, 0, 0, 5, 0, 4, 13, 2, 7, 0, 0, 7, 6, 1, 0, 0, 0, 53, 0, 0, 0, 90, 1, 0, 5, 0, 2, 0, 1, 1, 0, 12, 1, 0, 3, 61, 0, 0, 0, 0, 0, 0, 2, 117, 7, 0, 2, 10, 0, 0, 1, 23, 1, 1, 1, 0, 0, 1, 0, 5, 1, 0, 3, 2, 2, 568, 1, 1, 1, 4, 1, 5, 9, 3, 0, 22, 1, 0, 9, 2, 1, 7, 0, 2, 10, 1, 1, 0
Offset: 0

Views

Author

Antti Karttunen, Oct 04 2015

Keywords

Crossrefs

Cf. A262892 (positions of zeros).
Cf. A262893 (partial sums).
Cf. also A255330.

Programs

  • Scheme
    (define (A262890 n) (let ((t (A259934 n))) (let loop ((s 0) (k (A262686 t))) (cond ((<= k t) s) ((= t (A049820 k)) (loop (+ s (A262697 k)) (- k 1))) (else (loop s (- k 1)))))))

Formula

a(n) = Sum_{k = A082284(A259934(n)) .. A262686(A259934(n))} [A049820(k) = A259934(n)] * A262697(k).
(Here [ ] stands for Iverson bracket, giving as its result 1 only when A049820(k) = A259934(n), and 0 otherwise.)
Other identities. For all n >= 0:
a(n) = A262888(n) + A262889(n).

A262696 a(n)=0 if n is in A259934, otherwise number of terminal nodes (including n itself if it is a leaf) in that finite subtree whose root is n and whose edge-relation is defined by A049820(child) = parent.

Original entry on oeis.org

0, 2, 0, 1, 1, 1, 0, 1, 1, 13, 1, 13, 0, 1, 1, 11, 1, 11, 0, 1, 1, 10, 0, 10, 1, 1, 1, 10, 1, 9, 0, 8, 1, 1, 0, 8, 1, 1, 6, 7, 1, 1, 0, 1, 1, 6, 0, 6, 5, 1, 1, 6, 1, 5, 0, 1, 1, 5, 0, 3, 4, 3, 0, 1, 1, 3, 1, 1, 1, 2, 0, 1, 4, 1, 1, 1, 7, 1, 0, 1, 1, 7, 1, 6, 4, 1, 1, 6, 1, 1, 0, 5, 1, 1, 0, 4, 4, 4, 1, 1, 1, 1, 0, 1, 3, 4, 0, 4, 1, 1, 1, 3, 1, 1, 0, 1, 1, 1, 0, 1, 3, 0, 4, 1
Offset: 0

Views

Author

Antti Karttunen, Oct 04 2015

Keywords

Examples

			For n=1, its transitive closure (as defined by edge-relation A049820(child) = parent) is the union of {1} itself together with all its descendants: {1, 3, 4, 5, 7, 8}. We see that there are no other nodes in a subtree whose root is 1, because A049820(3) = 3 - d(3) = 1, A049820(4) = 1, A049820(5) = 3, A049820(7) = 5, A049820(8) = 4 and of these only 7 and 8 are terms of A045765. Thus a(1) = 2.
For n=9, its transitive closure is {9, 11, 13, 15, 16, 17, 19, 21, 23, 24, 27, 29, 31, 33, 35, 36, 37, 39, 41, 43, 45, 47, 51, 53, 55, 57, 59, 61, 63, 64, 65, 67, 69, 71, 73, 75, 77, 79}, of which only thirteen members: {13, 19, 24, 33, 36, 37, 43, 55, 63, 64, 67, 75, 79} are leaves (in A045765), thus a(9) = 13.
		

Crossrefs

Formula

If A262693(n) = 1 [when n is in A259934],
then a(n) = 0,
otherwise, if A060990(n) = 0 [when n is one of the leaves, A045765],
then a(n) = 1,
otherwise:
a(n) = Sum_{k = A082284(n) .. A262686(n)} [A049820(k) = n] * a(k).
(In the last clause [ ] stands for Iverson bracket, giving as its result 1 only when A049820(k) = n, and 0 otherwise).
Other identities:
For any n in A262511 but not in A259934, a(n) = a(A082284(n)).

A262896 If n is in A262892, a(n) = A259934(n), otherwise the largest term in A045765 from which A259934(n) can be reached by iterating A049820, without visiting any other (larger) term of A259934.

Original entry on oeis.org

8, 2, 79, 12, 18, 40, 30, 140, 42, 52, 54, 66, 68, 123, 98, 90, 94, 116, 106, 126, 164, 121, 369, 133, 156, 168, 180, 184, 280, 229, 190, 194, 210, 218, 252, 246, 236, 242, 272, 254, 312, 324, 300, 364, 298, 302, 372, 356, 334, 342, 346, 354, 439, 366, 374, 390, 672, 414, 410, 438, 426, 460, 442, 452, 470, 466, 564, 496, 494, 524, 627, 530, 546, 558, 562, 566, 574, 592, 859, 660, 606, 642, 708, 650
Offset: 0

Views

Author

Antti Karttunen, Oct 06 2015

Keywords

Comments

a(n) is the largest leaf-node among the finite subtrees branching from node n in the infinite trunk (A259934) of the tree generated by edge-relation A049820(child) = parent, and A259934(n) itself if it is one of the nonbranching nodes (A262897).
Note that without (so far undetected) regularity in A262509, there is no a priori upper bound for the value of a(n), and for some n this might not even be finite, if it happens that contrary to its conjectured nature, A259934 is not the unique infinite component, but just the lexicographically earliest instance of multiple infinite branches of the tree. In that case we might consider this sequence to be well-defined only up to the least such node branching to multiple infinite components, or alternatively, we might mark the nonfinite values at those points with -1.

Crossrefs

Programs

  • Scheme
    (define (A262896 n) (let ((t (A259934 n))) (let loop ((m t) (k (A262686 t))) (cond ((<= k t) m) ((= t (A049820 k)) (loop (max m (A262522 k)) (- k 1))) (else (loop m (- k 1)))))))

Formula

a(n) = max(A259934(n), Max_{k = A082284(A259934(n)) .. A262686(A259934(n))} [A049820(k) = A259934(n)] * A262522(k)).
(Here [ ] stands for Iverson bracket, giving as its result 1 only when A049820(k) = A259934(n), and 0 otherwise).
Other identities. For all n >= 0:
A262904(a(n)) = n. [A262904 works as a left inverse for this sequence.]
A259934(n) = A262679(a(n)).
For all n >= 1:
a(A262892(n)) = A259934(A262892(n)) = A262897(n).

A265751 Square array A(row,col): A(row,0) = row and for col >= 1, if A082284(row) is 0, then A(row,col) = 0, otherwise A(row,col) = A(A082284(row),col-1).

Original entry on oeis.org

0, 1, 1, 3, 3, 2, 5, 5, 6, 3, 7, 7, 9, 5, 4, 0, 0, 11, 7, 8, 5, 0, 0, 13, 0, 0, 7, 6, 0, 0, 0, 0, 0, 0, 9, 7, 0, 0, 0, 0, 0, 0, 11, 0, 8, 0, 0, 0, 0, 0, 0, 13, 0, 0, 9, 0, 0, 0, 0, 0, 0, 0, 0, 0, 11, 10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 13, 14, 11, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 20, 13, 12, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 18, 13, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 22, 0, 14
Offset: 0

Views

Author

Antti Karttunen, Dec 21 2015

Keywords

Comments

The square array A(row>=0, col>=0) is read by downwards antidiagonals as: A(0,0), A(0,1), A(1,0), A(0,2), A(1,1), A(2,0), A(0,3), A(1,2), A(2,1), A(3,0), ...
Each row n lists all the nodes in A263267-tree that one encounters when one starts from node with number n and always chooses the smallest possible child of it [given by A082284(n)], and then the smallest possible child of that child, etc, until a leaf-child (one of the terms of A045765) is encountered, after which the rest of the row contains only zeros.

Examples

			The top left corner of the array:
   0,  1,  3,  5,  7,  0,  0,  0,  0
   1,  3,  5,  7,  0,  0,  0,  0,  0
   2,  6,  9, 11, 13,  0,  0,  0,  0
   3,  5,  7,  0,  0,  0,  0,  0,  0
   4,  8,  0,  0,  0,  0,  0,  0,  0
   5,  7,  0,  0,  0,  0,  0,  0,  0
   6,  9, 11, 13,  0,  0,  0,  0,  0
   7,  0,  0,  0,  0,  0,  0,  0,  0
   8,  0,  0,  0,  0,  0,  0,  0,  0
   9, 11, 13,  0,  0,  0,  0,  0,  0
  10, 14, 20,  0,  0,  0,  0,  0,  0
  11, 13,  0,  0,  0,  0,  0,  0,  0
  12, 18, 22, 25,  0,  0,  0,  0,  0
  13,  0,  0,  0,  0,  0,  0,  0,  0
  14, 20,  0,  0,  0,  0,  0,  0,  0
  15, 17, 19,  0,  0,  0,  0,  0,  0
  16, 24,  0,  0,  0,  0,  0,  0,  0
  17, 19,  0,  0,  0,  0,  0,  0,  0
  18, 22, 25,  0,  0,  0,  0,  0,  0
  19,  0,  0,  0,  0,  0,  0,  0,  0
  20,  0,  0,  0,  0,  0,  0,  0,  0
  21, 23, 27, 29, 31, 35, 37,  0,  0
  22, 25,  0,  0,  0,  0,  0,  0,  0
  23, 27, 29, 31, 35, 37,  0,  0,  0
  ...
Starting from n = 21, we get the following chain: 21 -> 23 -> 27 -> 29 -> 31 -> 35 -> 37, with A082284 iterated 6 times before the final nonzero term 37 (for which A060990(37) = A082284(37) = 0) is encountered. Thus the row 21 of array contains terms 21, 23, 27, 29, 31, 35, 37, followed by an infinite number of zeros.
		

Crossrefs

Cf. also A000005, A045765, A060990.
Column 0: A001477, Column 1: A082284.
Cf. A266111 (number of significant terms on each row, without the trailing zeros).
Cf. A266116 (the rightmost term before trailing zeros).
See also array A263271 constructed in the same way, but obtained by following always the largest child A262686, instead of the smallest child A082284.
Cf. also tree A263267 (and its illustration).

Programs

  • Scheme
    (define (A265751 n) (A265751bi (A002262 n) (A025581 n)))
    (define (A265751bi row col) (cond ((zero? col) row) ((A082284 row) => (lambda (lad) (if (zero? lad) lad (A265751bi lad (- col 1)))))))
    ;; Alternatively:
    (define (A265751bi row col) (cond ((zero? col) row) ((and (zero? row) (= 1 col)) 1) ((zero? (A265751bi row (- col 1))) 0) (else (A082284 (A265751bi row (- col 1))))))

Formula

A(row,0) = row and for col >= 1, if A082284(row) is 0, then A(row,col) = 0, otherwise A(row,col) = A(A082284(row),col-1).
A(0,0) = 0, A(0,1) = 1; if col = 0, A(row,0) = row; and for col > 0, if A(row,col-1) = 0, then A(row,col) = 0, otherwise A(row,col) = A082284(A(row,col-1)).

A262512 Sequence gives the unique x for each term of A262511 which contains those numbers n that have exactly one solution to x - d(x) = n, where d(n) is the number of divisors of n (A000005).

Original entry on oeis.org

6, 5, 8, 7, 11, 14, 18, 20, 17, 24, 22, 23, 27, 32, 34, 35, 40, 43, 46, 50, 47, 51, 57, 58, 61, 72, 65, 73, 84, 77, 81, 79, 88, 86, 87, 96, 92, 93, 94, 98, 99, 102, 97, 105, 101, 103, 120, 107, 114, 116, 119, 123, 125, 130, 135, 137, 143, 154, 160, 151, 155, 158, 164, 163, 175, 173, 177, 184, 179, 187, 198, 200, 191, 194, 193, 204, 210, 197, 203, 216, 206, 209, 212
Offset: 1

Views

Author

Antti Karttunen, Sep 25 2015

Keywords

Comments

Sequence is sorted by the magnitude of terms in A262511. Cf. also A262513.

Crossrefs

Cf. A262513 (same sequence sorted into ascending order).

Programs

  • Scheme
    (define (A262512 n) (let ((s (A262511 n))) (let loop ((k s)) (if (= s (A049820 k)) k (loop (+ 1 k))))))

Formula

a(n) = the least (and the only) such number k > A262511(n) that A049820(k) = A262511(n).
a(n) = A082284(A262511(n)).
a(n) = A262686(A262511(n)).

A262888 a(n) = total number of nodes in the finite subtrees branching "left" (to the "smaller side") from node n in the infinite trunk (A259934) of the tree generated by edge-relation A049820(child) = parent.

Original entry on oeis.org

6, 0, 41, 0, 0, 5, 0, 16, 0, 2, 0, 0, 1, 24, 4, 0, 0, 0, 0, 0, 0, 0, 105, 2, 0, 0, 0, 3, 18, 7, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 13, 1, 0, 0, 0, 0, 6, 1, 0, 0, 0, 47, 0, 0, 0, 90, 0, 0, 5, 0, 0, 0, 1, 0, 0, 12, 0, 0, 3, 61, 0, 0, 0, 0, 0, 0, 1, 117, 7, 0, 2, 10, 0, 0, 1, 23, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 2, 2, 2, 568, 0, 1, 1, 4, 0, 5, 9, 0, 0, 0, 0, 0, 8, 0, 1, 1, 0, 2, 10, 1, 1, 0
Offset: 0

Views

Author

Antti Karttunen, Oct 04 2015

Keywords

Crossrefs

Programs

  • Scheme
    (define (A262888 n) (let ((t (A259934 n))) (let loop ((s 0) (k (A259934 (+ 1 n)))) (cond ((<= k t) s) ((= t (A049820 k)) (loop (+ s (A262697 k)) (- k 1))) (else (loop s (- k 1)))))))

Formula

a(n) = sum_{k = A082284(A259934(n)) .. A259934(n+1)} [A049820(k) = A259934(n)] * A262697(k).
(Here [ ] stands for Iverson bracket, giving as its result 1 only when A049820(k) = A259934(n), and 0 otherwise).
Other identities. For all n >= 0:
A262890(n) = a(n) + A262889(n).

A262889 a(n) = total number of nodes in the finite subtrees branching "right" (to the "larger side") from node n in the infinite trunk (A259934) of the tree generated by edge-relation A049820(child) = parent.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 2, 0, 0, 0, 3, 0, 1, 13, 0, 0, 0, 1, 1, 2, 2, 0, 0, 0, 0, 0, 0, 2, 3, 0, 0, 5, 0, 4, 0, 1, 7, 0, 0, 7, 0, 0, 0, 0, 0, 6, 0, 0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 5, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 3, 0, 22, 1, 0, 1, 2, 0, 6, 0, 0, 0, 0, 0, 0
Offset: 0

Views

Author

Antti Karttunen, Oct 04 2015

Keywords

Crossrefs

Programs

Formula

a(n) = sum_{k = A259934(n+1) .. A262686(A259934(n))} [A049820(k) = A259934(n)] * A262697(k).
(Here [ ] stands for Iverson bracket, giving as its result 1 only when A049820(k) = A259934(n), and 0 otherwise).
Other identities. For all n >= 0:
A262890(n) = A262888(n) + a(n).

A262900 a(n) = number of leaf-children n has in the tree generated by edge-relation A049820(child) = parent.

Original entry on oeis.org

0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 2, 0, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 2, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 2, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 0, 1, 2, 0, 0, 1, 0, 0, 0, 1, 1, 1, 0
Offset: 0

Views

Author

Antti Karttunen, Oct 06 2015

Keywords

Comments

a(n) = number of such terms k in A045765 for which k - d(k) = n [where d(k) is the number of divisors of k, A000005(k)].

Examples

			a(4) = 1, as there is only one such term k in A045765 which satisfies the condition A049820(k) = 4, namely 8 (8 - d(8) = 4).
a(5) = 1, as the only term in A045765 satisfying the condition is 7, as 7 - d(7) = 5.
a(22) = 2, as there are exactly two terms in A045765 satisfying the condition, namely 25 and 28, as 25 - d(25) = 28 - d(28) = 22.
		

Crossrefs

Cf. A262901 (indices of nonzero terms), A262902.

Programs

  • Scheme
    (define (A262900 n) (let loop ((s 0) (k (A262686 n))) (cond ((<= k n) s) ((= n (A049820 k)) (loop (+ s (if (zero? (A060990 k)) 1 0)) (- k 1))) (else (loop s (- k 1))))))

Formula

a(n) = Sum_{k = A082284(n) .. A262686(n)} [A049820(k) = n] * [A060990(k) = 0].
In the above formula [ ] stands for Iverson bracket, giving in the first instance as its result 1 only when A049820(k) = n (that is, when k is really a child of n), and 0 otherwise, and in the second instance 1 only when A060990(k) = 0 (that is, when k itself has no children), and 0 otherwise. - Comment corrected by Antti Karttunen, Nov 27 2015

A263269 The right edge of irregular table A263267.

Original entry on oeis.org

0, 2, 6, 12, 18, 22, 30, 34, 42, 46, 54, 58, 66, 70, 80, 88, 94, 102, 112, 116, 126, 124, 130, 138, 150, 148, 160, 158, 164, 184, 190, 194, 210, 214, 222, 234, 252, 246, 250, 258, 266, 272, 296, 312, 306, 320, 328, 340, 352, 364, 372, 354, 358, 368, 384, 392, 408, 402, 414, 418, 426, 434, 448, 460, 462, 470, 474, 486, 496, 510, 522, 530, 546, 558, 562, 566, 574, 582, 592, 598, 606, 630
Offset: 0

Views

Author

Antti Karttunen, Nov 29 2015

Keywords

Crossrefs

Cf. A264988 (the other edge).

Formula

a(n) = A263267(A263260(n)-1).
Other identities. For all n >= 0:
A155043(a(n)) = n.
a(A262508(n)) = A262509(n) = A264988(A262508(n)). [In case A262508 and A262509 are infinite sequences.]
Previous Showing 11-19 of 19 results.