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A280919 Precipices from the successive terraces, descending by the main diagonal of the pyramid described in A245092. Also first differences of A071562. 11
1, 2, 2, 2, 1, 3, 3, 1, 2, 2, 4, 1, 3, 2, 2, 3, 1, 4, 2, 3, 3, 1, 1, 4, 2, 4, 3, 1, 2, 4, 2, 5, 3, 1, 3, 4, 2, 1, 5, 2, 1, 1, 4, 4, 2, 2, 5, 3, 1, 5, 2, 2, 2, 3, 5, 3, 1, 6, 3, 1, 2, 4, 2, 3, 3, 1, 1, 6, 4, 2, 5, 3, 2, 3, 1, 2, 2, 4, 4, 1, 1, 6, 4, 1, 3, 1, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Descending by the main diagonal of the pyramid, A071562 gives the levels where we can find a terrace.
The terraces at the k-th level of the pyramid are also the parts of the symmetric representation of sigma(k).
a(n) is the length of the n-th vertical line segment at the main diagonal of the pyramid.
a(n) is the precipice of A071562(n).
The structure of the stepped pyramid arises after the 90-degree-zig-zag folding of the diagram of the isosceles triangle A237593.
The stepped pyramid is also one of the 3D-quadrants of the stepped pyramid described in A244050.
Equals nonzero terms of A259179. - Omar E. Pol, Apr 17 2018
LINKS
FORMULA
a(n) = A280223(A071562(n)).
MATHEMATICA
Differences@ Select[Range@ 228, Function[n, Total@ Select[Divisors@ n, Sqrt[n/2] <= # < Sqrt[2 n] &] != 0]] (* Michael De Vlieger, Jan 13 2017, after Robert G. Wilson v at A071562 *)
CROSSREFS
For more information about the precipices see A276112, A277437, A280223 and A280295.
Sequence in context: A324100 A127953 A260418 * A209266 A359930 A269400
KEYWORD
nonn
AUTHOR
Omar E. Pol, Jan 10 2017
EXTENSIONS
More terms from Michael De Vlieger, Jan 13 2017
STATUS
approved

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Last modified February 21 12:33 EST 2024. Contains 370235 sequences. (Running on oeis4.)