A105814 a(n) = n^2 + (n concatenated with n).

12, 26, 42, 60, 80, 102, 126, 152, 180, 1110, 1232, 1356, 1482, 1610, 1740, 1872, 2006, 2142, 2280, 2420, 2562, 2706, 2852, 3000, 3150, 3302, 3456, 3612, 3770, 3930, 4092, 4256, 4422, 4590, 4760, 4932, 5106, 5282, 5460, 5640, 5822, 6006, 6192, 6380, 6570

Offset

1,1

Links

Michael S. Branicky, Table of n, a(n) for n = 1..10000

Formula

a(n) = n^2 + n*(1+10^(1+floor(log_10(n)))). - Robert Israel, Jul 30 2015

a(n) = n^2 + A020338(n). - Michel Marcus, Jul 31 2015

Example

1 + 11 = 12, 4 + 22 = 26, 9 + 33 = 42, 16 + 44 = 60, ..., 100 + 1010 = 1110.

Maple

seq(n^2 + n*(1+10^(1+ilog10(n))), n=1..100); # Robert Israel, Jul 30 2015

Mathematica

f[n_] := Block[{id = IntegerDigits[n]}, n^2 + FromDigits[ Join[id, id]]]; Table[ f[n], {n, 45}] (* Robert G. Wilson v, May 10 2005 *)

Prog

(PARI) vector(50, n, n^2 + eval(Str(n, n))) \\ Michel Marcus, Jul 31 2015
(Magma) [Seqint(Intseq(n) cat Intseq(n))+n^2: n in [1..50]] /* or */ [n^2+n*(1+10^(1+Floor(Log(n)/Log(10)))): n in [1..50]]; // Vincenzo Librandi, Jul 31 2015
(Python)
def a(n): return n**2 + int(str(n)*2)
print([a(n) for n in range(1, 47)]) # Michael S. Branicky, Dec 26 2021

Crossrefs

Cf. A020338.

Sequence in context: A054303 A184826 A119412 * A297427 A357893 A211115

Adjacent sequences: A105811 A105812 A105813 * A105815 A105816 A105817

Keyword

base,easy,nonn

Author

Eric Angelini, May 05 2005

Extensions

More terms from Robert G. Wilson v, May 10 2005

Status

approved