The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A102484 Numbers of the concatenated form 9nn9. 5
 9009, 9119, 9229, 9339, 9449, 9559, 9669, 9779, 9889, 9999, 910109, 911119, 912129, 913139, 914149, 915159, 916169, 917179, 918189, 919199, 920209, 921219, 922229, 923239, 924249, 925259, 926269, 927279, 928289, 929299, 930309 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Robert Israel, Table of n, a(n) for n = 1..10000 FORMULA a(n) = 9*(1 + 10^(2*A055642(n-1)+1))+(n-1)*(10+10^(1+A055642(n-1))). - Robert Israel, May 09 2017 EXAMPLE For n=0 we concatenate 3, 0, 0 and 3 to get 3003. For n=10 we concatenate 3, 10, 10 and 3 to get 310103. MAPLE f:= n -> 9 + 9*10^(2*ilog10(n-1)+3)+(n-1)*(10+10^(2+ilog10(n-1))): f(1):= 9009; map(f, [\$1..200]); # Robert Israel, May 09 2017 MATHEMATICA With[{k = {9}}, Table[FromDigits@ Join[k, #, #, k] &@ IntegerDigits[n], {n, 0, 30}]] (* Michael De Vlieger, May 09 2017 *) CROSSREFS Cf. A100846 for 1nn1; A100896 for 3nn3; A100897 for 7nn7. Cf. A055642. Sequence in context: A202531 A106770 A326319 * A295457 A252456 A196994 Adjacent sequences:  A102481 A102482 A102483 * A102485 A102486 A102487 KEYWORD easy,nonn,base AUTHOR Mark Hudson (mrmarkhudson(AT)hotmail.com), Jan 12 2005 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified June 1 11:05 EDT 2020. Contains 334762 sequences. (Running on oeis4.)