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 A143538 Triangle read by rows, T(n,k) = 1 if k is prime, 0 otherwise; 1 <= k <= n. 3
 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Row sums = A000720, PrimePi(n), the number of primes through n: (0, 1, 2, 2, 3, 3, 4, 4, 4, 4, ...). LINKS G. C. Greubel, Table of n, a(n) for the first 100 rows, flattened FORMULA Triangle read by rows, T(n,k) = 1 if k is prime, 0 otherwise; 1 <= k <= n. A000012 * (A010051 * 0^(n-k)). A010051 * 0^(n-k) = an infinite lower triangular matrix with A010051 (the characteristic function of the primes) as the main diagonal and the rest zeros. The multiplier A000012 takes partial sums of column terms. EXAMPLE First few rows of the triangle = 0; 0, 1; 0, 1, 1; 0, 1, 1, 0; 0, 1, 1, 0, 1; 0, 1, 1, 0, 1, 0; 0, 1, 1, 0, 1, 0, 1; ... MATHEMATICA Table[If[PrimeQ[k], 1, 0], {n, 1, 20}, {k, 1, n}] // Flatten (* G. C. Greubel, Sep 17 2017 *) PROG (PARI) for(n=1, 10, for(k=1, n, print1(if(isprime(k), 1, 0), ", "))) \\ G. C. Greubel, Sep 17 2017 CROSSREFS Cf. A000720, A010051. Sequence in context: A092436 A164056 A163539 * A011656 A043545 A094754 Adjacent sequences:  A143535 A143536 A143537 * A143539 A143540 A143541 KEYWORD nonn,tabl,changed AUTHOR Gary W. Adamson, Aug 23 2008 STATUS approved

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