A268728 Square array A(row,col) = B(row,(2*col)-1), where B(p,2q-1) = 0 if gcd(p,2q-1) > 1, and A269158(p,q) otherwise. Array is read by descending antidiagonals as A(1,1), A(1,2), A(2,1), A(1,3), A(2,2), A(3,1), ...
0, 0, 1, 0, 2, 1, 0, 7, 0, 0, 0, 4, 3, 0, 1, 0, 13, 3, 0, 2, 0, 0, 14, 0, 0, 0, 0, 1, 0, 11, 1, 0, 2, 4, 0, 1, 0, 8, 1, 0, 1, 7, 7, 2, 1, 0, 25, 0, 0, 1, 0, 0, 7, 0, 0, 0, 26, 3, 0, 6, 15, 5, 4, 0, 0, 1, 0, 31, 3, 0, 0, 10, 3, 13, 4, 0, 2, 1, 0, 28, 0, 0, 6, 0, 2, 14, 0, 6, 0, 0, 1, 0, 21, 1, 0, 1, 26, 7, 11, 4, 12, 0, 3, 0, 0
Offset: 1
Examples
The top left [1 .. 16] x [1 .. 25] section of the array: 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 1, 2, 7, 4, 13, 14, 11, 8, 25, 26, 31, 28, 21, 22, 19, 16 1, 0, 3, 3, 0, 1, 1, 0, 3, 3, 0, 1, 1, 0, 3, 3 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 1, 2, 0, 2, 1, 1, 6, 0, 6, 1, 5, 6, 0, 6, 5, 5 0, 0, 4, 7, 0, 15, 10, 0, 26, 25, 0, 29, 20, 0, 16, 19 1, 0, 7, 0, 5, 3, 2, 7, 2, 1, 0, 3, 1, 4, 5, 4 1, 2, 7, 4, 13, 14, 11, 8, 25, 26, 31, 28, 21, 22, 19, 16 1, 0, 0, 4, 0, 4, 9, 0, 12, 1, 0, 0, 12, 0, 4, 9 0, 0, 0, 6, 12, 15, 13, 0, 31, 27, 26, 26, 0, 16, 22, 21 1, 2, 0, 0, 13, 0, 7, 11, 14, 13, 14, 3, 8, 10, 10, 15 1, 0, 3, 3, 0, 1, 1, 0, 3, 3, 0, 1, 1, 0, 3, 3 1, 0, 3, 7, 0, 14, 0, 6, 1, 11, 14, 8, 8, 9, 12, 11 0, 2, 0, 0, 8, 13, 9, 15, 27, 27, 0, 31, 20, 18, 22, 20 1, 0, 0, 0, 0, 0, 11, 0, 9, 3, 0, 15, 0, 0, 2, 15 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 1, 2, 7, 3, 13, 15, 0, 8, 0, 8, 17, 11, 8, 14, 18, 10 0, 0, 7, 0, 0, 10, 2, 0, 21, 27, 0, 28, 25, 0, 23, 25 1, 0, 0, 2, 0, 14, 10, 0, 25, 0, 11, 19, 8, 9, 10, 16 1, 2, 0, 2, 1, 1, 6, 0, 6, 1, 5, 6, 0, 6, 5, 5 1, 0, 0, 0, 0, 15, 11, 0, 0, 26, 0, 10, 17, 0, 10, 15 0, 0, 7, 4, 0, 0, 12, 3, 23, 23, 17, 31, 29, 28, 25, 31 1, 2, 3, 4, 1, 0, 13, 8, 26, 0, 31, 0, 13, 19, 8, 11 0, 0, 4, 7, 0, 15, 10, 0, 26, 25, 0, 29, 20, 0, 16, 19 1, 0, 0, 0, 5, 1, 1, 0, 25, 25, 0, 28, 0, 12, 25, 13
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Crossrefs
Programs
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Scheme
(define (A268728 n) (A268728bi (A002260 n) (+ -1 (* 2 (A004736 n))))) (define (A268728bi p q) (if (not (odd? q)) (error "A268728bi: the second argument should be odd: " p q) (let loop ((p p) (q q) (s 0)) (cond ((zero? p) 0) ((= 1 p) s) ((odd? p) (loop (modulo q p) p (A003987bi s (A004198bi p q)))) (else (loop (/ p 2) q (A003987bi s (A003987bi q (/ (- q 1) 2))))))))) ;; Alternative implementation using the definition given in A269158: (define (A268728 n) (let ((p (A002260 n)) (q (+ -1 (* 2 (A004736 n))))) (if (< 1 (gcd p q)) 0 (A269158auxbi p q))))
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