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 A074463 #28 Sep 01 2025 19:58:54
%S A074463 2,3,5,7,2,4,5,2,4,9,3,4,3,5,5,2,4,4,4,4,8,6,2,6,3,4,6,5,2,4,4,7,6,6,
%T A074463 6,5,4,6,5,4,4,6,4,5,6,4,4,6
%N A074463 Average digit (rounded up) in the decimal expansion of a prime number p, where 2^p-1 is a Mersenne prime.
%F A074463 a(n) = A004427(A000043(n)). - _Amiram Eldar_, Oct 16 2024
%e A074463 Prime numbers for Mersenne: 2, 3, 5, 7, 13, 17, 19, 31, 61, ..., so the averages of digits rounded up are 2, 3, 5, 7, (1+3)/2=2, (1+7)/2=4, (1+9)/2=5, (3+1)/2=2, ceiling((6+1)/2)=4, ...
%t A074463 f[n_] := Block[{id = IntegerDigits@ n}, Ceiling[Plus @@ id/Length@ id]]; lst = { (* terms from A000043 *) }; f@# & /@ lst (* _Robert G. Wilson v_, Jun 26 2013 *)
%t A074463 Ceiling[Mean[IntegerDigits[#]]]&/@MersennePrimeExponent[Range[47]] (* _Harvey P. Dale_, Feb 01 2023 *)
%Y A074463 Cf. A000043, A004427, A074464.
%K A074463 nonn,base,more,changed
%O A074463 1,1
%A A074463 Y. Kelly Itakura (yitkr(AT)mta.ca), Aug 23 2002
%E A074463 a(43)-a(47) from _Ivan Panchenko_, Aug 03 2018
%E A074463 a(48) from _Amiram Eldar_, Oct 16 2024