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 A221645 Square array read by antidiagonals: T(n,k^2) = A040000(n) (= 1,2,2,2,...) if n=0 (mod k), T(n,k) = 0 else, n>=0, k>=1. 5
 1, 2, 0, 2, 0, 0, 2, 0, 0, 1, 2, 0, 0, 0, 0, 2, 0, 0, 2, 0, 0, 2, 0, 0, 0, 0, 0, 0, 2, 0, 0, 2, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 1, 2, 0, 0, 2, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 2, 0, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Other definition: Square array read by antidiagonal: T(n,k), n>=0, k>=1, in which column k lists the numbers A040000 (1, 2, 2, 2, 2...) interleaved with k^(1/2)-1 zeros, if k is a square otherwise column k lists only zeros. The sum of elements of the n-th antidiagonal equals the number of divisors of n. In other words, the antidiagonal sums give A000005. LINKS FORMULA sum_{k=1...n} a(n-k,k) = A000005(n) for all n>0. - M. F. Hasler, Feb 02 2013 EXAMPLE First 16 elements of first 16 rows of the square array are 1,0,0,1,0,0,0,0,1,0,0,0,0,0,0,1,... 2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,... 2,0,0,2,0,0,0,0,0,0,0,0,0,0,0,0,... 2,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,... 2,0,0,2,0,0,0,0,0,0,0,0,0,0,0,2,... 2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,... 2,0,0,2,0,0,0,0,2,0,0,0,0,0,0,0,... 2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,... 2,0,0,2,0,0,0,0,0,0,0,0,0,0,0,2,... 2,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,... 2,0,0,2,0,0,0,0,0,0,0,0,0,0,0,0,... 2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,... 2,0,0,2,0,0,0,0,2,0,0,0,0,0,0,2,... 2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,... 2,0,0,2,0,0,0,0,0,0,0,0,0,0,0,0,... 2,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,... ... For n = 3 the sum of the third antidiagonal is 2+0+0 = d(3) = A000005(3) = 2. For n = 16 the sum of the 16th antidiagonal is 2+0+0+2+0+0+0+0+0+0+0+0+0+0+0+1 = d(16) = A000005(16) = 5. PROG (PARI) A221645(n, m)={my(t); issquare(m, &t)||return; n||return(1); n%t & return; 2} \\ M. F. Hasler, Feb 02 2013 CROSSREFS Cf. A000005, A212119. Sequence in context: A248107 A035220 A227618 * A216176 A128765 A193511 Adjacent sequences:  A221642 A221643 A221644 * A221646 A221647 A221648 KEYWORD nonn,tabl AUTHOR Omar E. Pol, Feb 02 2013 STATUS approved

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Last modified April 22 04:39 EDT 2019. Contains 322329 sequences. (Running on oeis4.)