A272694 a(n) = (c(n)+f(c(n)))/2, where c() = A272693() and f(k) = sign(k)*(k mod 2).

0, -1, -1, -3, -2, -2, -2, 0, 3, 1, -2, -3, -4, -3, 1, 5, 2, -3, -5, -5, -2, 3, 6, 3, -5, -11, -6, 3, 7, 5, -3, -10, -9, -2, 8, 8, 1, -8, -11, -6, 6, 10, 5, -6, -13, -9, 1, 11, 8, -3, -11, -11, -2, 9, 12, 3, -11, -17, -8, 9, 18, 9, -11, -23, -12, 9, 19, 11, -9, -22, -15, 4, 20, 14, -6, -20, -17, 2, 19, 17

Offset: 0

Author

N. J. A. Sloane, Jun 08 2016

Keywords

• sign

Comments

Created in an attempt to simplify the definition of A108618.

Links

• N. J. A. Sloane, Table of n, a(n) for n = 0..10000

Crossrefs

Cf. A108618, A108619, A272693.

Programs

Maple

M:=1000;
a:=Array(0..M,0); # A108618 (with different offset)
b:=Array(0..M,0); # A108619 (with different offset)
c:=Array(0..M,0); # A272693
f:=n->sign(n)*(n mod 2);
a[0]:=0; b[0]:=0; c[0]:=0;
for n from 1 to M do
b[n]:=1+(a[n-1]+b[n-1])/2;
a[n]:=1+c[n-1]+f(c[n-1])+3*f(b[n]-1);
c[n]:=(a[n]-3*b[n])/2;
od:
[seq(a[n],n=0..M)];
[seq(b[n],n=0..M)];
[seq(c[n],n=0..M)];
[seq((c[n]+f(c[n]))/2,n=0..M)]; # A272694