A134803 Numbers n such that the sum of all numbers of the same parity <= n is equal to the sum of numbers of the opposite parity from n+1 to n+m, where m is odd and > 1.

3, 8, 119, 288, 4059, 9800

Offset

1,1

Links

Table of n, a(n) for n=1..6.

Example

3 -> 1+3 = 4 = 4
8 -> 2+4+6+8 = 20 = 9+11
119 -> 1+3+5+...+119 = 3600 = 120+122+...+168

Maple

P:=proc(n) local a, k, i, s1, s2; for i from 1 by 1 to n do if 2*trunc(i/2)=i then s1:=sum('2*k', 'k'=1..(i/2)); else s1:=sum('2*k-1', 'k'=1..(i+1)/2); fi; a:=1; s2:=i+1; while s1>s2 do a:=a+2; s2:=s2+i+a; od; if s1=s2 then lprint(i, s1); fi; od; end: P(10000);

Crossrefs

Cf. A001109, A084068, A089895.

Sequence in context: A123279 A361872 A279164 * A030063 A195568 A051047

Adjacent sequences: A134800 A134801 A134802 * A134804 A134805 A134806

Keyword

easy,nonn

Author

Paolo P. Lava and Giorgio Balzarotti, Jan 28 2008

Status

approved