A154382 a(n) = a(n-1) # n, where # is addition, subtraction, multiplication if prime(n) == respectively 0, 1, 2 (mod 3).

0, 2, 6, 2, 10, 4, 28, 20, 180, 1800, 1789, 1777, 23101, 23087, 346305, 5540880, 94194960, 94194942, 94194923, 1883898460, 1883898439, 1883898417, 43329663591, 1039911926184, 1039911926159, 27037710080134, 27037710080107, 757055882242996, 757055882242967

Offset

1,2

Links

Table of n, a(n) for n=1..29.

Example

a(2) = a(1) + 2 = 0 + 2 = 2 because prime(2) = 3 == 0 (mod 3).
a(3) = a(2) * 3 = 2 * 3 = 6 because prime(3) = 5 == 2 (mod 3).

Prog

(SageMath)
from itertools import islice
r, a = 0, []
for i, p in islice(enumerate(Primes()), 13):
    r = eval(f'r {"+-*"[p%3]} (i+1)')
    a.append(r)
print(a)

Crossrefs

Sequence in context: A002172 A126289 A200044 * A136762 A136697 A136761

Adjacent sequences: A154379 A154380 A154381 * A154383 A154384 A154385

Keyword

nonn

Author

Michael J Crowe (mjcrowe(AT)tiscali.co.uk), Jan 08 2009

Extensions

Edited and extended by Andrei Zabolotskii, Oct 31 2025

Status

approved