OFFSET
1,1
COMMENTS
LINKS
Paolo Xausa, Table of n, a(n) for n = 1..10000
EXAMPLE
30 is a term as 30-2, 30-4, 30-8, 30-16, i.e., 28, 26, 22 and 14 are all composites.
127 is a term (least odd term) as 127-2, 127-4, 127-8, 127-16, 127-32, 127-64, i.e., 125, 123, 119, 111, 95 and 63 are all composites.
34 is not a term as 34-32 = 2 is prime.
MAPLE
with(numtheory):
Suite1 := proc(N)
local n, k, m, L, test;
L := [];
for n from 4 to N do
test := true;
k := 1;
while 2^k < n do
m := n - 2^k;
if isprime(m) then
test := false;
break;
end if;
k := k+1;
od;
if test then
L := [op(L), n];
end if;
od;
return L;
end proc:
Suite1(150);
MATHEMATICA
Select[Range[8, 200], AllTrue[# - 2^Range[IntegerLength[#-1, 2] - 1], CompositeQ] &] (* Paolo Xausa, Jul 21 2026 *)
PROG
(PARI) isok(m) = if (m>2, for (k=1, logint(m, 2), my(c); if (isprime(c=m-2^k) || (c==1), return(0))); 1); \\ Michel Marcus, Jun 22 2026
CROSSREFS
KEYWORD
nonn
AUTHOR
Bernard Schott, Jun 20 2026
STATUS
approved