OFFSET
1,1
COMMENTS
There are infinitely many unlucky prime numbers, in particular all those of the form 6n - 1, eliminated in the second step of Ulam's procedure for lucky numbers. - Davide Rotondo, Aug 31 2020
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
MAPLE
L:= [seq(2*i+1, i=0..10^3)]:
for n from 2 while n < nops(L) do
r:= L[n];
L:= subsop(seq(r*i=NULL, i=1..nops(L)/r), L);
od:
U:= {2, seq(i, i=3..2*10^3+1, 2)} minus convert(L, set):
sort(convert(select(isprime, U), list)); # Robert Israel, Jul 26 2019
PROG
(SageMath)
# Copy from A000959 - (Robert FERREOL, Nov 19 2014)
def lucky(n):
L=list(range(1, n+1, 2)); j=1
while L[j] <= len(L)-1:
L=[L[i] for i in range(len(L)) if (i+1)%L[j]!=0]
j+=1
return(L)
[ p for p in prime_range(1000) if p not in lucky(1000) ] # Hauke Löffler, Jul 26 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Gabriel Finch (salsaman(AT)xs4all.nl), Oct 21 2009
STATUS
approved