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A100769
Beginning with 1, least positive integer not occurring earlier such that the n-th partial concatenation is a multiple of n.
4
1, 2, 3, 6, 5, 4, 16, 8, 9, 10, 14, 12, 20, 26, 35, 36, 37, 44, 7, 40, 31, 22, 19, 28, 25, 32, 39, 56, 60, 70, 43, 52, 49, 30, 15, 48, 51, 58, 59, 120, 50, 64, 93, 88, 65, 86, 61, 168, 101, 100, 57, 68, 13, 84, 155, 104, 158, 54, 127, 80, 133, 38, 78, 144, 45, 138, 18, 76
OFFSET
1,2
EXAMPLE
a(7) = 16 as the concatenation 12365416 of first seven terms is a multiple of 7. No number less than 16 and more than 6 fits in.
MATHEMATICA
a[1] = 1; a[n_] := a[n] = Block[{t = 1}, While[Mod[FromDigits@ Flatten[IntegerDigits /@ Join[Array[a, n - 1], {t}]], n] != 0 || MemberQ[Array[a, n - 1], t], t++]; t]; Array[a, 68] (* Giorgos Kalogeropoulos, May 07 2023 *)
PROG
(PARI) See Link section.
CROSSREFS
Sequence in context: A269373 A269374 A137761 * A353977 A023889 A327669
KEYWORD
base,easy,nonn
AUTHOR
Amarnath Murthy, Nov 27 2004
EXTENSIONS
More terms from Joshua Zucker, May 27 2005
STATUS
approved