OFFSET
1,7
COMMENTS
Equivalently, half the number of zeros in row n of A262045.
LINKS
N. J. A. Sloane, Table of n, a(n) for n = 1..512
FORMULA
MAPLE
r := proc(n) floor((sqrt(1+8*n)-1)/2) ; end proc: # A003056
A237048:=proc(n, k) local i; global r;
if n<(k-1)*k/2 or k>r(n) then return(0); fi;
if (k mod 2)=1 and (n mod k)=0 then return(1); fi;
if (k mod 2)=0 and ((n-k/2) mod k) = 0 then return(1); fi;
return(0);
end;
if n<(k-1)*k/2 or k>r(n) then return(0); fi;
add( (-1)^(i+1)*A237048(n, i), i=1..k);
end;
ct:=0;
for k from 1 to r(n) do if A249223(n, k)=0 then ct:=ct+1; fi; od:
ct;
end;
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jan 15 2021
STATUS
approved