A068793 a(n) = Sum_{i=1..n} i*(n^(n-i-1) + n^(n+i-1)).

5, 194, 14619, 1831444, 348288905, 94197694758, 34466324363639, 16416600747716168, 9876543210123456789, 7326247444821284733610, 6569987372181208872192659, 7007407167541356868004228892

Offset: 2

Author

Reinhard Zumkeller, Mar 04 2002

Keywords

• nonn

Comments

a(n) = A062813(n)*n^(n-1) + A023811(n).

a(n) is a palindrome in base-n representation for all n.

Examples

			a(2) = 5 = 101_2;
a(8) = 34466324363639 = 765432101234567_8;
a(10) = 9876543210123456789;
a(16) = 21173125052858393282329502187520773615 = FEDC...876543210123456789ABCDEF_16.
		

Crossrefs

Cf. A023811, A062813, A068792.

Programs

Python

def A068793(n): return ((m:=n**n)*(m*(n-2)+2)-n**2+n-1)//(n-1)**2 # Chai Wah Wu, Mar 18 2024

Formula

a(n) = (n^n*(n^n*(n-2)+2)-n^2+n-1)/(n-1)^2.