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A079809 Consider a triangle in which the 2n-th row contains first 2n positive integers in increasing order and the (2n+1)-st row contains first 2n+1 positive integers in decreasing order; sequence contains concatenation of numbers read upward at a 45-degree angle. 4
1, 1, 32, 12, 521, 143, 7234, 1632, 92541, 18345, 1127436, 1103652, 13294561, 11238547, 1521147638, 1143105672, 17213496581, 11631258749, 19215411678310, 1183145107692, 212174136985101, 120316512789411, 232194156118710312 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
LINKS
EXAMPLE
Triangle begins with:
1;
1 2;
3 2 1;
1 2 3 4;
5 4 3 2 1;
1 2 3 4 5 6;
MATHEMATICA
a[n_] := FromDigits[Join@@Table[IntegerDigits[If[OddQ[n+1-i], n+2-2i, i]], {i, 1, Ceiling[n/2]}]]
CROSSREFS
Sequence in context: A302893 A303628 A070616 * A070629 A304228 A305038
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Feb 10 2003
STATUS
approved

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Last modified April 16 08:27 EDT 2024. Contains 371698 sequences. (Running on oeis4.)