A231713 - OEIS

A231713

Square array A(i,j) = the sum of absolute values of digit differences in the matching positions of the factorial base representations of i and j, for i >= 0, j >= 0, read by antidiagonals.

0, 1, 1, 1, 0, 1, 2, 2, 2, 2, 2, 1, 0, 1, 2, 3, 3, 1, 1, 3, 3, 1, 2, 1, 0, 1, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 1, 0, 1, 2, 1, 2, 3, 3, 3, 3, 1, 1, 3, 3, 3, 3, 3, 2, 1, 2, 3, 0, 3, 2, 1, 2, 3, 4, 4, 2, 2, 4, 4, 4, 4, 2, 2, 4, 4, 2, 3, 2, 1, 2, 3, 0, 3, 2, 1, 2, 3, 2, 3, 3, 3, 3, 3, 3, 1, 1, 3, 3, 3, 3, 3, 3, 3, 2, 3, 2, 1, 2, 1, 0, 1, 2, 1, 2, 3, 2, 3

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OFFSET

0,7

COMMENTS

This table relates to the factorial base representation (A007623) in a similar way as A101080 relates to the binary system. See A230415 for another analog.

LINKS

Antti Karttunen, The first 121 antidiagonals of the table, flattened

FORMULA

Each entry A(i,j) >= A230415(i,j) and also each entry A(i,j) >= abs(A230419(i,j)).

EXAMPLE

The top left corner of this square array begins as:

0, 1, 1, 2, 2, 3, 1, 2, 2, 3, 3, ...

1, 0, 2, 1, 3, 2, 2, 1, 3, 2, 4, ...

1, 2, 0, 1, 1, 2, 2, 3, 1, 2, 2, ...

2, 1, 1, 0, 2, 1, 3, 2, 2, 1, 3, ...

2, 3, 1, 2, 0, 1, 3, 4, 2, 3, 1, ...

3, 2, 2, 1, 1, 0, 4, 3, 3, 2, 2, ...

1, 2, 2, 3, 3, 4, 0, 1, 1, 2, 2, ...

2, 1, 3, 2, 4, 3, 1, 0, 2, 1, 3, ...

2, 3, 1, 2, 2, 3, 1, 2, 0, 1, 1, ...

3, 2, 2, 1, 3, 2, 2, 1, 1, 0, 2, ...

3, 4, 2, 3, 1, 2, 2, 3, 1, 2, 0, ...

...

For example, A(1,2) = A(2,1) = 2 as 1 has factorial base representation '...0001' and 2 has factorial base representation '...0010', and adding the absolute values of the digit differences, we get 1+1 = 2.

On the other hand, A(3,5) = A(5,3) = 1, as 3 has factorial base representation '...0011' and 5 has factorial base representation '...0021', and they differ only by their second rightmost digit, the absolute value of difference being 1.

Note that as A007623(6)='100' and A007623(10)='120', we have A(6,10) = A(10,6) = 2.

PROG

(Scheme)

(define (A231713 n) (A231713bi (A025581 n) (A002262 n)))

(define (A231713bi x y) (let loop ((x x) (y y) (i 2) (d 0)) (cond ((and (zero? x) (zero? y)) d) (else (loop (floor->exact (/ x i)) (floor->exact (/ y i)) (+ i 1) (+ d (abs (- (modulo x i) (modulo y i)))))))))

CROSSREFS

The topmost row and the leftmost column: A034968.

Only the lower triangular region: A231714. Related tables: A230415, A230419. Cf. also A101080, A231717.

Sequence in context: A268038 A274923 A249071 * A340945 A224898 A027360

Adjacent sequences: A231710 A231711 A231712 * A231714 A231715 A231716

KEYWORD

nonn,base,tabl

AUTHOR

Antti Karttunen, Nov 12 2013

STATUS

approved