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
KEYWORD
base,easy,nonn
AUTHOR
Eric Angelini, May 05 2005
EXTENSIONS
More terms from Robert G. Wilson v, May 10 2005
STATUS
approved