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A100896
a(n) has decimal expansion 3nn3.
5
3003, 3113, 3223, 3333, 3443, 3553, 3663, 3773, 3883, 3993, 310103, 311113, 312123, 313133, 314143, 315153, 316163, 317173, 318183, 319193, 320203, 321213, 322223, 323233, 324243, 325253, 326263, 327273, 328283, 329293, 330303, 331313, 332323
OFFSET
0,1
LINKS
FORMULA
a(n) = 3nn3 where n=0, 1, 2, 3, ...
a(n) = 3*(1+10^(2*d+1))+n*(10+10^(d+1)) where d = A055642(n). - Robert Israel, Mar 08 2018
EXAMPLE
If n=5, then 3nn3 is 3553.
MAPLE
f:= proc(n) local d; d:= ilog10(n)+1; 3*(1+10^(2*d+1))+n*(10+10^(d+1)) end proc:
3003, seq(f(n), n=1..100); # Robert Israel, Mar 08 2018
MATHEMATICA
FromDigits/@Table[Join[{3}, IntegerDigits[i], IntegerDigits[i], {3}], {i, 0, 40}] (* Harvey P. Dale, Sep 22 2014 *)
PROG
(Magma) [3003] cat [3*(1+10^(2*#Intseq(n)+1))+n*(10+10^(#Intseq(n)+1)): n in [1..40]]; // Vincenzo Librandi, Mar 09 2018
CROSSREFS
Cf. A100846.
Sequence in context: A128935 A145304 A094336 * A324405 A140915 A140928
KEYWORD
nonn,base,easy
AUTHOR
Parthasarathy Nambi, Jan 10 2005
EXTENSIONS
More terms from Brian Lauer (bel136(AT)psu.edu), Feb 21 2006
Offset changed to 0 by Robert Israel, Mar 08 2018
STATUS
approved