OFFSET
1,1
COMMENTS
See A078569 for the primes arising in this sequence.
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..277
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 *)
Table[FromDigits[Join[PadRight[{}, n, 1], Flatten[IntegerDigits/@Range[n, 1, -1]]]], {n, 20}] (* Harvey P. Dale, Aug 23 2022 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Jason Earls, Nov 29 2002
STATUS
approved