login
Fixed points of A075075.
3

%I #26 Oct 26 2024 21:17:38

%S 1,2,8,36,39,49,370,626,632,1030,13155,32317,61358,86704,2535431,

%T 13360009

%N Fixed points of A075075.

%C A075075(a(n)) = A160516(a(n)) = a(n);

%C A075075(a(n)-1) * A075075(a(n)+1) mod a(n) = 0.

%o (Haskell)

%o a185635 n = a185635_list !! (n-1)

%o a185635_list = filter (> 0) $

%o zipWith (\x y -> if x == y then y else 0) [1..] a075075_list

%o -- _Reinhard Zumkeller_, Dec 19 2012

%o (Python)

%o from math import gcd

%o A185635_list, l1, l2, m, b = [1, 2], 2, 1, 2, {1, 2}

%o for n in range(3, 10**4):

%o i = m

%o while True:

%o if not i in b:

%o if n == i:

%o A185635_list.append(i)

%o l1, l2, m = i, l1, i//gcd(l1, i)

%o b.add(i)

%o break

%o i += m # _Chai Wah Wu_, Dec 09 2014

%K nonn,more

%O 1,2

%A _Reinhard Zumkeller_, Dec 19 2012

%E a(15) from _Chai Wah Wu_, Dec 10 2014

%E a(16) from _Chai Wah Wu_, Sep 22 2019