A009440 a(n) is the concatenation of n and 6n.

16, 212, 318, 424, 530, 636, 742, 848, 954, 1060, 1166, 1272, 1378, 1484, 1590, 1696, 17102, 18108, 19114, 20120, 21126, 22132, 23138, 24144, 25150, 26156, 27162, 28168, 29174, 30180, 31186, 32192, 33198, 34204, 35210, 36216, 37222, 38228, 39234, 40240

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Mathematica

nxt[n_]:=Module[{idn=IntegerDigits[n], idn6=IntegerDigits[6n]}, FromDigits[Join[idn, idn6]]]; Array[nxt, 100] (* Vincenzo Librandi, Feb 04 2014 *)
Table[n*10^IntegerLength[6n]+6n, {n, 40}] (* Harvey P. Dale, Jul 21 2020 *)

Prog

(Magma) [Seqint(Intseq(6*n) cat Intseq(n)): n in [1..50]]; // Vincenzo Librandi, Feb 04 2014

Crossrefs

Cf. concatenation of n and k*n: A020338 (k=1), A019550 (k=2), A019551 (k=3), A019552 (k=4), A019553 (k=5), this sequence (k=6), A009441 (k=7), A009470 (k=8), A009474 (k=9).

Sequence in context: A319236 A222447 A059385 * A284226 A282395 A273588

Adjacent sequences: A009437 A009438 A009439 * A009441 A009442 A009443

Keyword

nonn,base,less,easy

Author

David W. Wilson

Status

approved