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A127064
a(0)=1. a(n) = a(prime(n)(mod n)) + 1, where prime(n) is the n-th prime.
1
1, 2, 3, 4, 5, 3, 3, 5, 5, 4, 5, 5, 3, 4, 3, 4, 4, 6, 6, 6, 6, 6, 5, 4, 7, 6, 5, 6, 5, 6, 5, 5, 5, 4, 5, 5, 6, 5, 6, 6, 5, 5, 5, 7, 7, 7, 5, 5, 6, 6, 7, 7, 6, 7, 6, 6, 7, 6, 7, 6, 6, 7, 8, 7, 7, 8, 8, 8, 9, 4, 5, 5, 6, 4, 5, 6, 5, 6, 6, 4, 5, 4, 6, 5, 5, 4, 5, 4, 7, 5, 5, 4, 7, 6, 7, 8, 5, 8, 6, 6, 6, 6, 6, 7, 7
OFFSET
0,2
EXAMPLE
The 7th prime, 17, is congruent to 3 (mod 7). So a(7) = a(3) + 1 = 4 + 1 = 5.
MAPLE
a[0]:=1: for n from 1 to 125 do a[n]:=1+a[ithprime(n) mod n] od: seq(a[n], n=0..125); # Emeric Deutsch, Mar 25 2007
MATHEMATICA
f[l_List] := Block[{n = Length[l]}, Append[l, l[[Mod[Prime[n], n] + 1]] + 1]]; Nest[f, {1}, 105] (* Ray Chandler, Mar 25 2007 *)
PROG
(PARI) a(n)={k=1; if(n>0, k=a(prime(n)%n)+1); k; } \\ Jinyuan Wang, Feb 01 2019
CROSSREFS
Sequence in context: A343252 A341355 A104413 * A279850 A117607 A215092
KEYWORD
nonn
AUTHOR
Leroy Quet, Mar 21 2007
EXTENSIONS
Extended by Ray Chandler and Emeric Deutsch, Mar 25 2007
STATUS
approved