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 A169903 #10 Feb 10 2025 03:12:48 %S A169903 21,23,25,27,29,51,56,201,209,227,229,241,243,261,263,287,289,551, %T A169903 2023,2027,2043,2047,2061,2069,2081,2089,2207,2209,2221,2223,2263, %U A169903 2267,2281,2287,2401,2407,2421,2423,2441,2449,2483,2489,2603,2609 %N A169903 Primitive primes in carryless arithmetic mod 10. %C A169903 Define the units in carryless arithmetic mod 10 to be the numbers 1, 3, 7 and 9 (these divide any number). A prime is a number N, not a unit, whose only factorizations are of the form N = u * M, where u is a unit. %C A169903 A prime is primitive if it is not the carryless product of a smaller prime and a unit. %C A169903 A subsequence of A169887. %H A169903 David Applegate, <a href="/A169903/b169903.txt">Table of n, a(n) for n = 1..843</a> (all primitive primes with <= 6 digits) %H A169903 <a href="/index/Ca#CARRYLESS">Index entries for sequences related to carryless arithmetic</a> %Y A169903 Cf. A004520, A059729, A168294, A168541, A169885, A169886, A169884, A169887. %Y A169903 Cf. A058943, A058945. %K A169903 nonn,base %O A169903 1,1 %A A169903 _David Applegate_, _Marc LeBrun_ and _N. J. A. Sloane_, Jul 11 2010