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A026601
a(n) = n-th number k such that s(k) = 1, where s = A026600.
It appears that a(n) gives the position of its own n-th 1 modulo 3 term, the n-th 2 modulo 3 term in A026602, and the n-th multiple of 3 in A026603. A026602 and A026603 appear to have analogous indexical properties. [From Matthew Vandermast, Oct 06 2010]