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 A360324 #27 Feb 04 2023 20:47:27
%S A360324 1,13,313,1359,245895,131186351,468729047,1830140937
%N A360324 Numbers k such that k divides Sum_{i=1..k} 10^(1 + floor(log_10(p(i)))) - 1 - p(i), where p(i) is the i-th prime number.
%C A360324 Alternative Name : The arithmetic mean of the first k 9's complements of primes is an integer.
%F A360324 k: (Sum_{i=1..k} 10^(1 + floor(log_10(p(i)))) - 1 - p(i)) / k = c, c an integer.
%e A360324 k = 13: first 13 prime numbers are {2,3,5,7,11,13,17,19,23,29,31,37,41}, their 9's complements are {7,6,4,2,88,86,82,80,76,70,68,62,58} and (7 + 6 + ... + 62 + 58) / 13 = 53, thus 13 is a term.
%t A360324 s = 0; p = 2; pow = 10; seq = {}; Do[s += pow - 1 - p; If[Divisible[s, k], AppendTo[seq, k]]; p = NextPrime[p]; If[p > pow, pow *= 10], {k, 1, 250000}]; seq (* _Amiram Eldar_, Feb 04 2023 *)
%Y A360324 Cf. A000040, A045345, A055642, A061601.
%K A360324 nonn,more
%O A360324 1,2
%A A360324 _Ctibor O. Zizka_, Feb 04 2023
%E A360324 a(5)-a(8) from _Amiram Eldar_, Feb 04 2023