A225653 Numbers n such that A225634(n) = A225644(n).

0, 1, 21, 30, 33, 35, 36, 40, 42, 44, 48, 51, 52, 56, 57, 58, 60, 62, 63, 65, 66, 68, 69, 70, 72, 74, 75, 76, 77, 78, 80, 82, 84, 85, 88, 91, 92, 96

Offset

0,3

Comments

Positions of zeros in A225654.

Links

Table of n, a(n) for n=0..37.

Prog

(Scheme with Antti Karttunen's IntSeq-library):
(define A225653 (MATCHING-POS 0 0 inA225653?))
(define (inA225653? n) (or (zero? n) (let ((fun1 (lambda (seed) (let ((max1 (list 0))) (fold_over_partitions_of n 1 lcm (lambda (p) (set-car! max1 (max (car max1) (lcm seed p))))) (car max1)))) (fun2 (lambda (seed) (let ((max2 (list 0))) (fold_over_partitions_of n n lcm (lambda (p) (set-car! max2 (max (car max2) (lcm seed p))))) (car max2))))) (equal-steps-to-convergence-nondecreasing? fun1 fun2 1 n))))
(define (equal-steps-to-convergence-nondecreasing? fun1 fun2 initval1 initval2) (let loop ((steps 0) (a1 initval1) (a2 initval2)) (cond ((equal? a1 a2) (zero? steps)) ((< a1 a2) (loop (+ steps 1) (fun1 a1) a2)) (else (loop (- steps 1) a1 (fun2 a2))))))
(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))))))))
;; Alternatively, but somewhat slower, as:
(define A225653v2 (MATCHING-POS 0 0 (lambda (i) (= (A225634 i) (A225644 i)))))

Crossrefs

Cf. A225648, A225649, A225650, A225651, A225654.

Sequence in context: A043195 A043975 A215965 * A363609 A336357 A317772

Adjacent sequences: A225650 A225651 A225652 * A225654 A225655 A225656

Keyword

nonn

Author

Antti Karttunen, May 16 2013

Status

approved