|
|
A073920
|
|
a(1)=1 and then odd numbers rearranged such that a(n) is prime if n is composite else vice versa.
|
|
3
|
|
|
1, 9, 15, 3, 21, 5, 25, 7, 11, 13, 27, 17, 33, 19, 23, 29, 35, 31, 39, 37, 41, 43, 45, 47, 53, 59, 61, 67, 49, 71, 51, 73, 79, 83, 89, 97, 55, 101, 103, 107, 57, 109, 63, 113, 127, 131, 65, 137, 139, 149, 151, 157, 69, 163, 167, 173, 179, 181, 75, 191, 77, 193, 197, 199
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
MATHEMATICA
|
a = {1}; Do[k = 3; While[Nand[! MemberQ[a, k], Xor @@ Map[PrimeQ, {k, n}]], k += 2]; AppendTo[a, k], {n, 2, 64}]; a (* Michael De Vlieger, Mar 30 2017 *)
|
|
PROG
|
(PARI) nextcomposite(c) = until (!isprime(c), c +=2); c;
lista(nn) = {print1(1, ", "); p = 2; c = 1; for (n=2, nn, if (isprime(n), c = nextcomposite(c); print1(c, ", "), p = nextprime(p+1); print1(p, ", ")); ); } \\ Michel Marcus, Apr 01 2017
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
Extended and edited by T. D. Noe, Apr 13 2009
|
|
STATUS
|
approved
|
|
|
|