A363093 Leading digit of 7^n.

1, 7, 4, 3, 2, 1, 1, 8, 5, 4, 2, 1, 1, 9, 6, 4, 3, 2, 1, 1, 7, 5, 3, 2, 1, 1, 9, 6, 4, 3, 2, 1, 1, 7, 5, 3, 2, 1, 1, 9, 6, 4, 3, 2, 1, 1, 7, 5, 3, 2, 1, 1, 8, 6, 4, 3, 2, 1, 1, 7, 5, 3, 2, 1, 1, 8, 5, 4, 2, 2, 1, 1, 7, 4, 3, 2, 1, 1, 8, 5, 4, 2, 1, 1, 9, 6, 4, 3, 2, 1, 1, 8, 5, 3, 2, 1, 1, 9, 6, 4, 3

Offset: 0

Author

Seiichi Manyama, Jul 15 2023

Keywords

• nonn
• base
• easy

Crossrefs

Cf. A008952, A060956, A111395, A362871, A363249, A364185.

Cf. A000030, A000420, A001903, A008568.

Programs

Mathematica

a[n_] := IntegerDigits[7^n][[1]]; Array[a, 100, 0] (* Amiram Eldar, Jul 15 2023 *)

PARI

a(n) = digits(7^n)[1];

Formula

a(n) = A000030(A000420(n)).