OFFSET
1,1
LINKS
Chai Wah Wu, Table of n, a(n) for n = 1..10000
H. T. Engstrom, On sequences defined by linear recurrence relations Trans. Am. Math. Soc. 33 (1) (1931) 210-218.
K. Kirthi, Narayana Sequences for Cryptographic Applications, arXiv preprint arXiv:1509.05745 [math.NT], 2015.
M. B. Nathanson, Linear recurrences and uniform distribution, Proc. Amer. Math. Soc. 48 (1975), 289-291.
D. D. Wall, Fibonacci series modulo m, Amer. Math. Monthly, 67 (1960), 525-532.
FORMULA
a(n) = A271953(prime(n)). - Joerg Arndt, Apr 17 2016
MATHEMATICA
a[n_] := Module[{p = Prime[n], a = 1, b = 1, c = 2, k = 1}, While[a != 1 || b != 1 || c != 1, {a, b, c} = {b, c, Mod[a + c, p]}; k++]; k];
Array[a, 100] (* Jean-François Alcover, Jul 22 2018, after Charles R Greathouse IV *)
PROG
(Python)
from sympy import prime
def A271901(n):
p = prime(n)
i, a, b, c = 1, 1, 1, 2 % p
while a != 1 or b != 1 or c != 1:
i += 1
a, b, c = b, c, (a+c) % p
return i # Chai Wah Wu, Feb 26 2017
(PARI) a(n, p=prime(n))=my(a=1, b=1, c=2, k=1); while(a!=1 || b!=1 || c!=1, [a, b, c]=[b, c, (a+c)%p]; k++); k \\ Charles R Greathouse IV, Feb 26 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, Apr 17 2016
EXTENSIONS
a(1) corrected by Altug Alkan, Apr 17 2016
Terms a(24) and beyond from Joerg Arndt, Apr 17 2016
STATUS
approved