|
|
A278515
|
|
Number of steps required to iterate map k -> A255131(k) when starting from k = (A000196(n)+1)^2 before n is reached, or 0 if n is not reached.
|
|
2
|
|
|
1, 0, 0, 1, 0, 0, 2, 0, 1, 0, 0, 2, 0, 0, 0, 1, 4, 0, 3, 0, 0, 2, 0, 0, 1, 0, 0, 4, 0, 0, 3, 0, 2, 0, 0, 1, 0, 0, 5, 0, 4, 0, 0, 3, 0, 2, 0, 0, 1, 0, 0, 5, 0, 4, 0, 0, 3, 0, 0, 2, 0, 0, 0, 1, 7, 0, 0, 6, 0, 0, 5, 0, 4, 0, 0, 3, 0, 0, 2, 0, 1, 0, 0, 7, 0, 6, 0, 0, 5, 0, 4, 0, 0, 3, 0, 0, 2, 0, 0, 1, 0, 0, 7, 0, 0, 6, 0, 0, 5, 0, 0, 0, 4, 0, 0, 3, 0, 2, 0, 0, 1
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,7
|
|
LINKS
|
|
|
EXAMPLE
|
For n=15, we start iterating from the next larger square, (⌊√15⌋+1)^2 = 16, and in just a single step (16 - A002828(16) = 15) we land to n, so a(15) = 1.
For n=16, we start iterating from the next larger square, which is 25, and thus we have 25 -> A255131(25) = 24, 24 -> A255131(24) = 21, 21 -> A255131(21) = 18, 18 -> A255131(18) = 16, thus four steps were required to reach 16, and a(16) = 4.
For n=17, when we do the same iteration, we see that we will pass by it, thus a(17) = 0.
|
|
PROG
|
(Scheme) (define (A278515 n) (let* ((r (A000196 n)) (end (A000290 r))) (let loop ((k (A000290 (+ 1 r))) (s 0)) (cond ((= k n) s) ((<= k end) 0) (else (loop (A255131 k) (+ 1 s)))))))
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|