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 A294821 Irregular triangle read by rows: T(n,k) = 1 if k is the largest divisor of n <= sqrt(n), otherwise T(n,k) = 0. With n >= 1, and 1 <= k <= A000196(n). 1
 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1 COMMENTS The first element of column k is in the row k^2. LINKS FORMULA T(n, A033676(n)) = 1. T(n,k) = 0 if k is not equal to A033676(n), n >= 1, and 1 <= k <= A000196(n). a(n) = A057427(A294721(n)). EXAMPLE Triangle begins: 1; 1; 1; 0, 1; 1, 0; 0, 1; 1, 0; 0, 1; 0, 0, 1; 0, 1, 0; 1, 0, 0; 0, 0, 1; 1, 0, 0; 0, 1, 0; 0, 0, 1; 0, 0, 0, 1; 1, 0, 0, 0; 0, 0, 1, 0; 1, 0, 0, 0; 0, 0, 0, 1; 0, 0, 1, 0; 0, 1, 0, 0; 1, 0, 0, 0; 0, 0, 0, 1; 0, 0, 0, 0, 1; ... MATHEMATICA Table[ReplacePart[ConstantArray[0, IntegerPart@ Sqrt@ n], SelectFirst[Reverse@ Divisors@ n, # <= Sqrt@ n &] -> 1], {n, 32}] // Flatten (* Michael De Vlieger, Nov 13 2017 *) PROG (PARI) row(n) = {d = divisors(n); kmax = vecmax(select(x->(x^2 <= n), d)); vector(sqrtint(n), k, k==kmax); } tabf(nn) = for (n=1, nn, print(row(n))); \\ Michel Marcus, Dec 12 2017 CROSSREFS Row n has length A000196(n). Row sums give A000012. Cf. A033676, A057427, A163280, A237273, A294721. Sequences related to columns 1..12: A008578, A161344, A161345, A161424, A161835, A162527, A162527, A162528, A162529, A162530, A162531, A162532. Sequence in context: A105589 A097806 A167374 * A132971 A085357 A011748 Adjacent sequences:  A294818 A294819 A294820 * A294822 A294823 A294824 KEYWORD nonn,tabf AUTHOR Omar E. Pol, Nov 09 2017 STATUS approved

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Last modified February 21 18:45 EST 2019. Contains 320376 sequences. (Running on oeis4.)