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 A261806 #37 Oct 22 2024 15:13:51
%S A261806 7,474,42311,3558614,300169143,25814402881,2261786350515,
%T A261806 200839375217041,18042305628036066,1636922369808190765,
%U A261806 149754058084293423958,13797718194530764325852,1279006935910516590640721,119184789951429474863414128,11157358746329927416919291238,1048709967153503078344158238498
%N A261806 a(n) = Sum from "least x such that prime(x) has n digits" to "the number of primes with n digits" of the difference between prime(k) and k.
%H A261806 Lucas A. Brown, <a href="https://github.com/lucasaugustus/oeis/blob/main/A261806.py">Python program</a>.
%F A261806 a(n) = Sum_{k=A090226(n)..A006879(n)} prime(k)-k
%e A261806 As 2, 3, 5, and 7 are the only primes less than 10, A006879(1) = 4 and as 1 is the least number such that prime(1) has 1 digit, A090226(1) = 1. Therefore a(1) = Sum_{k=1..4} prime(k)-k = (2-1) + (3-2) + (5-3) + (7-4) = 1 + 1 + 2 + 3 = 7.
%Y A261806 Cf. A006879, A014689, A090226.
%K A261806 nonn,base
%O A261806 1,1
%A A261806 _Carauleanu Marc_, Jul 09 2016
%E A261806 a(7)-a(16) from _Lucas A. Brown_, Oct 21 2024