A362190 - OEIS

A362190

Triangle read by rows: T(n,k) is the smallest integer not already in the same row or column and also not diagonally adjacent to an equal integer.

0, 1, 2, 3, 0, 1, 2, 4, 3, 0, 5, 1, 2, 4, 3, 4, 3, 0, 1, 2, 5, 6, 5, 4, 3, 0, 1, 2, 7, 8, 6, 2, 4, 3, 0, 1, 9, 10, 5, 7, 1, 2, 4, 3, 0, 8, 6, 9, 10, 5, 0, 1, 2, 4, 3, 10, 7, 8, 6, 9, 4, 3, 0, 1, 2, 5, 11, 9, 10, 5, 7, 6, 8, 4, 3, 0, 1, 2

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OFFSET

1,3

COMMENTS

This sequence is A025581 without diagonal adjacent restriction.

LINKS

Neal Gersh Tolunsky, Table of n, a(n) for n = 1..10000

EXAMPLE

Triangle begins:

n\k| 1 2 3 4 5 6 7 8 ...

---+----------------------------

1 | 0

2 | 1 2

3 | 3 0 1

4 | 2 4 3 0

5 | 5 1 2 4 3

6 | 4 3 0 1 2 5

7 | 6 5 4 3 0 1 2

8 | 7 8 6 2 4 3 0 1

PROG

(PARI) \\ here f(S) gives smallest not in set S.

f(S)={for(k=0, oo, if(!setsearch(S, k), return(k)))}

T(n)={my(M=matrix(n, n)); for(i=2, n, for(j=1, i, my(S=Set(concat([M[j..i-1, j]~, M[i, 1..j-1], M[i-1, max(1, j-1)], M[i-1, min(j+1, i-1)]]))); M[i, j]=f(S))); M}

{ my(A=T(10)); for(i=1, #A, print(A[i, 1..i])) } \\ Andrew Howroyd, Apr 10 2023

CROSSREFS

Cf. A025581.

Sequence in context: A279681 A053645 A212598 * A274650 A294648 A356784

Adjacent sequences: A362187 A362188 A362189 * A362191 A362192 A362193

KEYWORD

nonn,easy,tabl

AUTHOR

Gavin Lupo, Apr 10 2023

STATUS

approved