A125119 Values of repunits with odd length L in base (L+3)/2 representation.

1, 13, 341, 19531, 2015539, 329554457, 78536544841, 25736391511831, 11111111111111111, 6115909044841454629, 4182283628124518315101, 3479492117784426363920483, 3461445831219105624193478971

Offset: 1

Author

Reinhard Zumkeller, Nov 21 2006

Keywords

• nonn
• base

Comments

Central terms of the triangle in A125118: a(n)=A125118(2*n-1,n).

Examples

			a(4) = [1111111]_5 = (((((5+1)*5+1)*5+1)*5+1)*5+1)*5+1 = 19531.
		

Links

• Eric Weisstein's World of Mathematics, Repunit

Formula

a(n) = Sum((n+1)^k: 0<=k<=2*(n-1)).