OFFSET
1,1
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
30 has 8 divisors. 30 in binary is 11110. 8 in binary is 1000. The string 1000 does not occur anywhere in the string 11110. So 30 occurs in this sequence.
MAPLE
filter:= proc(n) local L, t, Lt, m, mt;
L:= convert(n, base, 2);
m:= nops(L);
Lt:= convert(numtheory:-tau(n), base, 2);
mt:= nops(Lt);
andmap(i -> L[i..i+mt-1]<>Lt, [$1..m-mt+1]);
end proc:
select(filter, [$1..1000]); # Robert Israel, Jun 17 2021
MATHEMATICA
bndQ[n_]:=Module[{bn=IntegerDigits[n, 2], dn=IntegerDigits[ DivisorSigma[ 0, n], 2]}, !MemberQ[ Partition[ bn, Length[dn], 1], dn]]; Select[Range[ 200], bndQ] (* Harvey P. Dale, Nov 01 2013 *)
Select[Range[200], SequenceCount[IntegerDigits[#, 2], IntegerDigits[DivisorSigma[0, #], 2]]==0&] (* Harvey P. Dale, Oct 13 2024 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Leroy Quet, Aug 03 2008
EXTENSIONS
Extended by Ray Chandler, Nov 09 2008
STATUS
approved