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 A278113 Triangle T(n,k) = A278112(n,A000040(k)) for 1 <= k <= A278114(n), read by rows. 4
 1, 2, 1, 1, 1, 3, 2, 1, 1, 1, 1, 1, 4, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 5, 4, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 6, 4, 3, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 7, 5, 4, 3, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 8, 6, 5, 4, 3, 3, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS This triangle consists of those columns of A278112 that have prime index. LINKS Jason Kimberley, Table of n, a(i) for i = 1..10126 (T(n,k) for n = 1..46 FORMULA T(n,k) = floor(n*sqrt(2/prime(k))). T(n,k) sqrt(A000040(k)) <= n sqrt(2) < (T(n,k)+1) sqrt(A000040(k)). EXAMPLE The first eight rows are: 1; 2, 1, 1, 1; 3, 2, 1, 1, 1, 1, 1; 4, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1; 5, 4, 3, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1; 6, 4, 3, 3, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1; 7, 5, 4, 3, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1; 8, 6, 5, 4, 3, 3, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1; MATHEMATICA Table[Floor[n Sqrt[2/Prime@ k]], {n, 8}, {k, PrimePi[2 n^2]}] // Flatten (* Michael De Vlieger, Feb 17 2017 *) PROG (MAGMA) A278112:=func; A278113_row:=func; &cat[A278113_row(n):n in[1..8]]; CROSSREFS Cf. A000040, A277648, A278112, A278114, A278115, A278118. Sequence in context: A319864 A072776 A077481 * A242012 A086290 A136568 Adjacent sequences:  A278110 A278111 A278112 * A278114 A278115 A278116 KEYWORD nonn,tabf,easy AUTHOR Jason Kimberley, Feb 09 2017 STATUS approved

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Last modified January 22 16:42 EST 2019. Contains 319364 sequences. (Running on oeis4.)