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A078262
Sum of the forward and reverse concatenations of 1 to n.
1
2, 33, 444, 5555, 66666, 777777, 8888888, 99999999, 1111111110, 23333333231, 2345555545332, 244567776755433, 25466789897765534, 2647689001998775635, 274869910212099785736, 28497092031222200795837, 2950719304132232301805938
OFFSET
1,1
LINKS
EXAMPLE
a(3) = 123 +321 = 444,a(10) = 12345678910 + 10987654321 = 23333333231.
MATHEMATICA
Table[With[{c1=FromDigits[Flatten[IntegerDigits/@Range[n]]], c2= FromDigits[ Flatten[ IntegerDigits/@Range[n, 1, -1]]]}, c1+c2], {n, 20}] (* Harvey P. Dale, Jul 03 2020 *)
CROSSREFS
Cf. A078263.
Sequence in context: A100023 A336969 A119300 * A118117 A231794 A083143
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Nov 24 2002
EXTENSIONS
More terms from Sascha Kurz, Jan 04 2003
STATUS
approved