a(n) is the exponent of the least power of 2 such that the concatenated digits of the decimal expansion of 2^n are a proper substring of the concatenated digits of the decimal expansion of 2^a(n).

A342575

a(n) is the exponent of the least power of 2 such that the concatenated digits of the decimal expansion of 2^n are a proper substring of the concatenated digits of the decimal expansion of 2^a(n).

Terms

    a(0) =4a(1) =5a(2) =6a(3) =7a(4) =14a(5) =15a(6) =26a(7) =102a(8) =103a(9) =104a(10) =224a(11) =103a(12) =104a(13) =105a(14) =506a(15) =507a(16) =452a(17) =1169a(18) =1170a(19) =1171a(20) =8228a(21) =10419a(22) =15186a(23) =5227a(24) =16619a(25) =16620a(26) =16621a(27) =25102a(28) =130090a(29) =62640

External references