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 1-3 of 3 results.

A225634 a(n) = Number of distinct values in column n of A225630.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, May 13 2013

Keywords

Comments

Also, for n>=1, a(n) = the length of n-th row of A225632.
For the positions of records, and other remarks, see comments at A225633.

Crossrefs

Cf. A225635 (partial sums).

Programs

  • Scheme
    (define (A225634 n) (count_number_of_distinct_lcms_of_partitions_until_fixed_point_met n 1))
    (define (count_number_of_distinct_lcms_of_partitions_until_fixed_point_met n initial_value) (let loop ((lcms (list initial_value initial_value))) (fold_over_partitions_of n 1 lcm (lambda (p) (set-car! lcms (max (car lcms) (lcm (second lcms) p))))) (if (= (car lcms) (second lcms)) (length (cdr lcms)) (loop (cons (car lcms) lcms)))))
    (define (fold_over_partitions_of m initval addpartfun colfun) (let recurse ((m m) (b m) (n 0) (partition initval)) (cond ((zero? m) (colfun partition)) (else (let loop ((i 1)) (recurse (- m i) i (+ 1 n) (addpartfun i partition)) (if (< i (min b m)) (loop (+ 1 i))))))))

Formula

a(n) = A225638(n)+A226056(n).
a(n) = A225633(n) + 1.

A225629 a(n) = Last value in column n of A225630 which is not yet the fixed point A003418(n) of that column.

Original entry on oeis.org

1, 1, 1, 3, 4, 30, 30, 84, 120, 1260, 840, 13860, 13860, 180180, 180180, 180180, 240240, 6126120, 6126120, 116396280, 58198140, 116396280, 116396280, 2677114440, 2677114440, 13385572200, 13385572200, 40156716600, 40156716600, 776363187600, 776363187600
Offset: 0

Views

Author

Antti Karttunen, May 13 2013

Keywords

Comments

a(n) = also the second rightmost terms of row n of irregular table A225632.
a(0)= a(1) = 1 by convention.

Crossrefs

Programs

Formula

a(n) = A225630(n,max(0,A225633(n)-1)).

A225643 Number of steps to reach a fixed point (A003418(n)), when starting from partition {n} of n and continuing with the process described in A225642.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, May 15 2013

Keywords

Comments

a(0)=0, as its only partition is an empty partition {}, and by convention lcm()=1, thus it takes no steps to reach from 1 to A003418(0)=1.
The records occur at positions 0, 3, 5, 9, 11, 13, 19, 27, 30, 33, 43, 44, 51, 65, 74, 82, ... and they seem to occur in order, i.e., as A001477. Thus the record-positions probably also give the left inverse function for this sequence. It also seems that each integer occurs only finite times in this sequence, so there should be a right inverse function as well.

Crossrefs

Programs

Formula

a(n) = A225644(n) - 1.
Showing 1-3 of 3 results.