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A078568 Repunits concatenated with A000422, where A000422 is the concatenation of numbers from n down to 1. 1
11, 1121, 111321, 11114321, 1111154321, 111111654321, 11111117654321, 1111111187654321, 111111111987654321, 111111111110987654321, 111111111111110987654321, 111111111111121110987654321 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

See A078569 for the primes arising in this sequence.

LINKS

Table of n, a(n) for n=1..12.

MATHEMATICA

a[n_Integer] := Block[{repUn = Array[Array[1 &, #] &, {n}], nTo1 = Range[ Range@n, 1, -1]}, ToExpression/@ StringJoin/@ Map[ToString, Flatten/@ Thread@{repUn, nTo1}, {2}]]; a[100] (* or *)

a[n_Integer] := FromDigits /@ StringJoin /@ Table[ Join[ PadLeft[{}, i, "1"], ToString /@ Range[i, 1, -1]], {i, n}]; a[100] (* Mikk Heidemaa, May 03 2021 *)

CROSSREFS

Cf. A002275, A000422, A078569.

Sequence in context: A343837 A303067 A075600 * A015095 A167118 A045981

Adjacent sequences:  A078565 A078566 A078567 * A078569 A078570 A078571

KEYWORD

base,nonn

AUTHOR

Jason Earls, Nov 29 2002

STATUS

approved

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Last modified August 4 15:31 EDT 2021. Contains 346447 sequences. (Running on oeis4.)