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A152597
Where records occur in A001917.
4
2, 4, 11, 21, 31, 110, 124, 185, 279, 399, 716, 1028, 4552, 6207, 6543, 11424, 11557, 12251, 16199, 23043, 43390, 155798, 203095, 457523, 699782, 865318, 1294026, 2918851, 5635889, 6459777, 8999147, 9213126, 22383796, 28194383, 32131750, 105097565, 404165580
OFFSET
1,1
LINKS
FORMULA
a(n) = A000720(A226216(n)). - Amiram Eldar, Nov 16 2023
EXAMPLE
First few terms of A001917 (has offset 2) are 1, 1, 2, 1, 1, 2, 1, 2, 1, 6, so a(1) to a(3) are 2, 4, 11.
PROG
(Magma) W:=[]; r:=0; for n in [2..100000] do p:=NthPrime(n); a:=(p-1)/Modorder(2, p); if r lt a then r:=a; Append(~W, n); end if; end for; print W;
(Python)
from itertools import islice
from sympy import nextprime, n_order
def agen():
record, v, p = -1, 1, 3
while True:
if v > record: record = v; yield record
v, p = (p-1)//n_order(2, p), nextprime(p)
print(list(islice(agen(), 20))) # Michael S. Branicky, Oct 09 2022
CROSSREFS
Cf. A001917 ((p-1)/x, where p = prime(n) and x = smallest positive integer such that 2^x == 1 mod p), A152598 (records in A001917), A000720, A226216.
Sequence in context: A278446 A349566 A026275 * A320679 A126972 A295947
KEYWORD
nonn
AUTHOR
Klaus Brockhaus, Dec 09 2008
EXTENSIONS
a(27)-a(37) from Amiram Eldar, Mar 08 2019
STATUS
approved