OFFSET
1,2
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..10000
A. Karttunen, Ratio a(n)/A278168(n) plotted with OEIS Plot 2 tool
EXAMPLE
For n=4, starting from k = ((4+1)^2)-1, and iterating k -> A255131(k), yields 24 -> 21 -> 18 -> 16 -> 15 -> 11 -> 8 -> 6 -> 3 before 0 is reached. Subtracting one from each gives [23, 20, 17, 15, 14, 10, 7, 5, 2], of which only 23, 17, 7, 5 and 2 are primes, thus a(4) = 5.
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Nov 13 2016
STATUS
approved