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A257564 Irregular triangle read by rows: T(n,k) = r(n+k)+r(n-k) with r(n) = (n-(n mod 2))/2 for n>=0 and -n<=k<=n. 2
0, 1, 0, 1, 2, 1, 2, 1, 2, 3, 2, 3, 2, 3, 2, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5, 6, 5, 6, 5, 6, 5, 6, 5, 6, 5, 6, 5, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 8, 7, 8, 7, 8, 7, 8, 7, 8, 7, 8, 7, 8, 7, 8, 7, 8 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

COMMENTS

r(n+k)-r(n-k) is triangle A196199(n,k).

LINKS

Table of n, a(n) for n=0..80.

FORMULA

Sum_{k=-n..n} T(n,k) = 2*n^2 = A001105(n).

EXAMPLE

Triangle starts:

                 0;

              1, 0, 1;

           2, 1, 2, 1, 2;

        3, 2, 3, 2, 3, 2, 3;

     4, 3, 4, 3, 4, 3, 4, 3, 4;

  5, 4, 5, 4, 5, 4, 5, 4, 5, 4, 5;

MAPLE

r := n -> (n-(n mod 2))/2: T := (n, k) -> r(n+k) + r(n-k):

seq(print(seq(T(n, k), k=-n..n)), n=0..6);

PROG

(Sage)

for n in (0..6):

    [(n+k)//2 + (n-k)//2 for k in (-n..n)]

CROSSREFS

Cf. A001105, A196199, A253580.

Sequence in context: A085243 A265745 A092243 * A194509 A054716 A261641

Adjacent sequences:  A257561 A257562 A257563 * A257565 A257566 A257567

KEYWORD

tabf,easy,nonn

AUTHOR

Peter Luschny, May 28 2015

STATUS

approved

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Last modified April 20 09:59 EDT 2019. Contains 322309 sequences. (Running on oeis4.)