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 A138239 Triangle read by rows: T(n,k) = A000040(k) if A002445(n) mod A000040(k) = 0, otherwise 1. 4
 1, 2, 3, 2, 3, 5, 2, 3, 1, 7, 2, 3, 5, 1, 1, 2, 3, 1, 1, 11, 1, 2, 3, 5, 7, 1, 13, 1, 2, 3, 1, 1, 1, 1, 1, 1, 2, 3, 5, 1, 1, 1, 17, 1, 1, 2, 3, 1, 7, 1, 1, 1, 19, 1, 1, 2, 3, 5, 1, 11, 1, 1, 1, 1, 1, 1, 2, 3, 1, 1, 1, 1, 1, 1, 23, 1, 1, 1, 2, 3, 5, 7, 1, 13, 1, 1, 1, 1, 1, 1, 1, 2, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Row products give A002445. A prime number appears in a column at every A130290-th row from the (A130290+1)-th row onwards. The prime numbers are, so to speak, equidistantly distributed in the columns. A130290 is essentially A005097. Counting terms > 1 in the rows gives A046886. LINKS Michel Marcus, Rows n=0..100 of triangle, flattened EXAMPLE First few rows of the triangle and row products are: 1 = 1 2*3 = 6 2*3*5 = 30 2*3*1*7 = 42 2*3*5*1*1 = 30 2*3*1*1*11*1 = 66 2*3*5*7*1*13*1 = 2730 MAPLE T:= (n, k)-> (p-> `if`(irem(denom(bernoulli(2*n)), p)=0, p, 1))(ithprime(k)): seq(seq(T(n, k), k=1..n+1), n=0..20);  # Alois P. Heinz, Aug 27 2017 MATHEMATICA t[n_, k_] := If[Mod[Denominator[BernoulliB[2n]], (p = Prime[k])] == 0, p, 1]; Flatten[Table[t[n, k], {n, 0, 13}, {k, 1, n+1}]][[1 ;; 102]] (* Jean-François Alcover, Jun 16 2011 *) PROG (PARI) tabl(nn) = {for (n=0, nn, dbn = denominator(bernfrac(2*n)); for (k=1, n+1, if (! (dbn % prime(k)), w = prime(k), w = 1); print1(w, ", "); ); print; ); } \\ Michel Marcus, Aug 27 2017 CROSSREFS Cf. A002445, A005097, A046886, A130290. Sequence in context: A098235 A114868 A249049 * A112484 A174063 A124459 Adjacent sequences:  A138236 A138237 A138238 * A138240 A138241 A138242 KEYWORD nonn,tabl AUTHOR Mats Granvik, Mar 07 2008 EXTENSIONS Definition edited by N. J. A. Sloane, Mar 18 2010 Offset corrected by Alois P. Heinz, Aug 27 2017 STATUS approved

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Last modified January 20 12:50 EST 2019. Contains 319330 sequences. (Running on oeis4.)