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A154791 Triangle read by rows in which row n lists all the pairs of noncomposite numbers that are equidistant from n, with 0's inserted, as shown below in the example. 1
0, 1, 3, 1, 0, 5, 1, 3, 5, 7, 0, 3, 0, 7, 0, 1, 0, 5, 7, 0, 11, 1, 3, 0, 0, 0, 11, 13, 0, 3, 5, 0, 0, 11, 13, 0, 1, 0, 5, 7, 0, 11, 13, 0, 17, 1, 3, 0, 7, 0, 0, 13, 0, 17, 19, 0, 3, 5, 0, 0, 0, 0, 0, 17, 19, 0, 1, 0, 5, 7, 0, 11, 13, 0, 17, 19, 0, 23 (list; table; graph; refs; listen; history; text; internal format)
OFFSET
1,3
LINKS
EXAMPLE
Triangle begins:
n ....... Pairs
1 ..........0
2 ........ 1,3
3 ....... 1,0,5
4 ...... 1,3,5,7
5 ..... 0,3,0,7,0
6 .... 1,0,5,7,0,11
PROG
(PARI) iscomp(n) = (n!=1) && !isprime(n);
vecp(n) = {v = vector(n, i, 2*i-1); for (i = 1, n\2, if (iscomp(v[i]) || iscomp(v[n-i+1]), v[i] = 0; v[n-i+1] = 0); ); if ((n % 2), v[n\2+1] = 0); v; }
trgp(nn) = {for (n = 1, nn, v = vecp(n); for (k = 1, n, print1(v[k], ", "); ); print(); ); } \\ Michel Marcus, Feb 13 2014
CROSSREFS
Sequence in context: A134560 A127626 A245095 * A121440 A348016 A353092
KEYWORD
nonn,tabl
AUTHOR
Omar E. Pol, Jan 25 2009
EXTENSIONS
More terms from Michel Marcus, Feb 13 2014
STATUS
approved

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Last modified July 21 20:59 EDT 2024. Contains 374475 sequences. (Running on oeis4.)