A077695 a(n) = triangular number pertaining to the number f(n) obtained by concatenating n n times.

1, 253, 55611, 9876790, 1543206790, 222222111111, 30246911419753, 3950617249382716, 499999999500000000, 51015202530354045509590858075706560555, 617283950617283950617716049382716049382716

Offset

1,2

Comments

a(n) = triangular number corresponding to A000461(n).

Links

Harvey P. Dale, Table of n, a(n) for n = 1..166

Example

a(4) = 9876790 = 4444*4445/2.

Mathematica

(#(#+1))/2&/@Table[FromDigits[Flatten[IntegerDigits/@PadRight[{}, n, n]]], {n, 15}] (* Harvey P. Dale, Oct 15 2021 *)

Crossrefs

Cf. A077692, A077693, A077694, A000461.

Sequence in context: A255182 A176087 A006060 * A253880 A145628 A237419

Adjacent sequences: A077692 A077693 A077694 * A077696 A077697 A077698

Keyword

base,nonn

Author

Amarnath Murthy, Nov 18 2002

Extensions

More terms from Sascha Kurz, Jan 07 2003

Status

approved