This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A351904 #33 Mar 13 2022 19:06:19 %S A351904 1,3,2,7,9,11,4,15,10,19,6,14,24,27,8,31 %N A351904 a(n) is the smallest number k such that the symmetric representation of sigma(k) has at least one subpart n. %C A351904 Conjecture: there are infinitely many pairs of the form a(x) = y; a(y) = x (see examples). %C A351904 First differs from A351903 at a(11). %e A351904 For n = 11 we have that 6 is the smallest number k with at least one subpart 11 in the symmetric representation of sigma(k), so a(11) = 6. %e A351904 The symmetric representation of sigma(6) in the first quadrant looks like this: %e A351904 . %e A351904 _ _ _ _ %e A351904 |_ _ _ |_ 1 %e A351904 | |_|_ 11 %e A351904 |_ _ | %e A351904 | | %e A351904 | | %e A351904 |_| %e A351904 . %e A351904 There are one subpart 11 and one subpart 1. %e A351904 . %e A351904 Some pairs of the form a(x) = y; a(y) = x: %e A351904 a(2) = 3; a(3) = 2. %e A351904 a(4) = 7; a(7) = 4. %e A351904 a(6) = 11; a(11) = 6. %e A351904 a(8) = 15; a(15) = 8. %e A351904 a(16) = 31; a(31) = 16. %e A351904 . %Y A351904 Row 1 of A352015. %Y A351904 Cf. A351903 (Analog for parts). %Y A351904 Cf. A000079, A000203, A000225, A001227 (number of subparts), A196020, A235791, A236104, A237270, A237271, A237591, A237593, A279387 (definition of subparts), A280850, A280851 (subparts), A296508, A296513, A347529, A351819. %K A351904 nonn,more %O A351904 1,2 %A A351904 _Omar E. Pol_, Feb 25 2022