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A108422 Greatest number of ones that can be used to write in binary representation 2*n as sum of two primes. 3
2, 4, 4, 5, 5, 6, 5, 6, 6, 6, 6, 6, 6, 7, 6, 7, 7, 8, 7, 8, 8, 8, 7, 8, 8, 9, 7, 8, 9, 10, 7, 8, 8, 9, 8, 9, 9, 10, 8, 9, 9, 8, 9, 10, 10, 10, 8, 8, 9, 9, 9, 10, 10, 10, 9, 9, 8, 10, 10, 10, 8, 10, 8, 9, 9, 10, 9, 10, 10, 9, 9, 10, 9, 11, 9, 10, 11, 12, 9, 10, 10, 10, 10, 11, 9, 12, 8, 9, 11, 10, 8, 12 (list; graph; refs; listen; history; text; internal format)
OFFSET
2,1
COMMENTS
a(n) = Max{A000120(p)+A000120(q): p,q prime and p+q=2*n);
a(n) = A108423(n) + A108421(n).
LINKS
MAPLE
N:= 200: # to get a(2)..a(N)
Primes:= select(isprime, [seq(i, i=3..2*N-3, 2)]):
Ones:= map(t -> convert(convert(t, base, 2), `+`), Primes):
V:= Vector(N): V[2]:= 2:
for i from 1 to nops(Primes) do
p:= Primes[i];
for j from 1 to i do
k:= (p+Primes[j])/2;
if k > N then break fi;
t:= Ones[i]+Ones[j];
if t > V[k] then V[k]:= t fi
od
od:
convert(V[2..N], list); # Robert Israel, Mar 26 2018
CROSSREFS
Sequence in context: A036443 A036437 A053306 * A276523 A244320 A084616
KEYWORD
nonn,base
AUTHOR
Reinhard Zumkeller, Jun 03 2005
STATUS
approved

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Last modified March 28 16:12 EDT 2024. Contains 371254 sequences. (Running on oeis4.)