A232710 Binary numbers (written in decimal) such that the sum of digits mod 2 equals the product of digits mod 2.

0, 1, 5, 6, 7, 9, 10, 12, 17, 18, 20, 23, 24, 27, 29, 30, 31, 33, 34, 36, 39, 40, 43, 45, 46, 48, 51, 53, 54, 57, 58, 60, 65, 66, 68, 71, 72, 75, 77, 78, 80, 83, 85, 86, 89, 90, 92, 95, 96, 99, 101, 102, 105, 106, 108, 111, 113, 114, 116, 119, 120, 123, 125

Offset

0,3

Links

Table of n, a(n) for n=0..62.

Index entries for sequences related to binary expansion of n

Formula

A083420 UNION (A001969 \ {3}). - Ralf Stephan, Nov 30 2013

Example

23 is in the sequence because 23 in binary is 10111. The sum of digits is 4 == 0 mod 2 and the products of digits is 0 == 0 mod 2.

Prog

(JavaScript)
for (i=0; i<1000; i++) {
s=i.toString(2).split("");
sl=s.length;
c=0; d=1;
for (j=0; j<sl; j++) {c+=s[j]*1; d*=s[j]; }
c%=2; d%=2;
if (c==d) document.write(i+", ");
}
(PARI) is(n)=b=binary(n); sum(i=1, #b, b[i])%2==prod(i=1, #b, b[i])%2 \\ Ralf Stephan, Nov 30 2013

Crossrefs

Sequence in context: A246782 A089192 A279195 * A132829 A180061 A196029

Adjacent sequences: A232707 A232708 A232709 * A232711 A232712 A232713

Keyword

nonn,base

Author

Jon Perry, Nov 28 2013

Status

approved