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A173556 Triangle T(n,m) = (prime(n)-1)*(prime(m)- 1) mod 8 read by rows. 0
1, 2, 4, 4, 0, 0, 6, 4, 0, 4, 2, 4, 0, 4, 4, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 4, 0, 4, 4, 0, 0, 4, 6, 4, 0, 4, 4, 0, 0, 4, 4, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4, 6 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Row sums are: 1, 6, 4, 14, 14, 4, 0, 18, 26, 4,...

LINKS

Table of n, a(n) for n=1..106.

FORMULA

t(n,m)=Mod[(Prime[n] - 1)*(Prime[m] - 1), 8]

EXAMPLE

The triangle (prime(n)-1)*(prime(m)-1) starts

1;

2,4 ;

4,8,16 ;

6,12,24,36 ;

10,20,40,60,100 ;

12,24,48,72,120,144 ;

16,32,64,96,160,192,256 ;

and reduced mod 8, T(n,m) starts

1;

2, 4;

4, 0, 0;

6, 4, 0, 4;

2, 4, 0, 4, 4;

4, 0, 0, 0, 0, 0;

0, 0, 0, 0, 0, 0, 0;

2, 4, 0, 4, 4, 0, 0, 4;

6, 4, 0, 4, 4, 0, 0, 4, 4;

4, 0, 0, 0, 0, 0, 0, 0, 0, 0;

MATHEMATICA

t[n_, m_] = Mod[(Prime[n] - 1)*(Prime[m] - 1), 8];

Table[Table[t[n, m], {m, 1, n}], {n, 1, 10}];

Flatten[%]

CROSSREFS

Sequence in context: A163089 A258371 A111172 * A247554 A198786 A176531

Adjacent sequences: A173553 A173554 A173555 * A173557 A173558 A173559

KEYWORD

nonn,tabl,easy

AUTHOR

Roger L. Bagula, Feb 21 2010

EXTENSIONS

Standardized nomenclature - the Assoc. Editors of the OEIS, Feb 24 2010

STATUS

approved

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Last modified December 5 12:42 EST 2022. Contains 358586 sequences. (Running on oeis4.)