Numbers k that divide the concatenation of sigma(k-1) and sigma(k+1).

Terms

a(0) =2a(1) =55a(2) =56a(3) =93a(4) =170a(5) =944a(6) =1904a(7) =2839a(8) =3104a(9) =4213a(10) =4793a(11) =4953a(12) =5664a(13) =35120a(14) =48456a(15) =145256a(16) =213416a(17) =224288a(18) =267084a(19) =276736a(20) =310897a(21) =366624a(22) =627850a(23) =802024a(24) =837801a(25) =1093671a(26) =1451332a(27) =2036312a(28) =2909925a(29) =3888750