login
A105814
a(n) = n^2 + (n concatenated with n).
1
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
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
KEYWORD
base,easy,nonn
AUTHOR
Eric Angelini, May 05 2005
EXTENSIONS
More terms from Robert G. Wilson v, May 10 2005
STATUS
approved