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Replace each entry 2^i(2j+1) of the triangle in A008280 with i and replace 0's with *'s; then the entries n in the new triangle do not occur beyond diagonal a(n), measured from the left edge and taking the left edge to be diagonal number 1.
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%I #15 Nov 06 2018 13:17:41

%S 2,4,4,4,8,8,8,8,10,12,12,16,16,16,16,16,18,20

%N Replace each entry 2^i(2j+1) of the triangle in A008280 with i and replace 0's with *'s; then the entries n in the new triangle do not occur beyond diagonal a(n), measured from the left edge and taking the left edge to be diagonal number 1.

%H V. I. Arnold, <a href="http://dx.doi.org/10.1215/S0012-7094-91-06323-4">Bernoulli-Euler updown numbers associated with function singularities, their combinatorics and arithmetics</a>, Duke Math. J. 63 (1991), 537-555.

%H Sanjay Ramassamy, <a href="https://arxiv.org/abs/1712.08666">Modular periodicity of the Euler numbers and a sequence by Arnold</a>, arXiv:1712.08666 [math.CO], 2017.

%e 3's do not occur beyond the 4th diagonal, so a(3) = 4.

%e Triangle begins:

%e *

%e * 0

%e 0 0 *

%e * 0 1 1

%e 0 0 2 1 *

%e * 0 1 1 4 4

%Y Cf. A008280.

%K nonn,more

%O 0,1

%A _N. J. A. Sloane_, Jun 01 2005

%E Corrected and extended by _Sanjay Ramassamy_, Nov 03 2018