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 A068820 #11 Mar 12 2025 08:19:59 %S A068820 2,3,11,13,47,53,97,131,197,241,409,431,607,673,739,751,983,991,1103, %T A068820 1433,1489,1531,1553,1709,1721,2371,2393,2447,2633,2789,2833,2897, %U A068820 3041,3109,3217,3371,3373,3527,3547,3593,3671,3691,4057,4153,4211,4297,4363 %N A068820 Ulam numbers that are primes. %H A068820 Charles R Greathouse IV, <a href="/A068820/b068820.txt">Table of n, a(n) for n = 1..49221</a> %H A068820 Shyam Sunder Gupta, <a href="https://doi.org/10.1007/978-981-97-2465-9_18">Ulam Numbers</a>. In: Exploring the Beauty of Fascinating Numbers. Springer Praxis Books(). Springer, Singapore, (2025). %p A068820 # Function 'UlamList' is defined in A002858. %p A068820 UlamPrimes := n -> select(k->isprime(k), UlamList(n)): %p A068820 UlamPrimes(403); # _Peter Luschny_, Apr 05 2019 %Y A068820 Cf. A002858. %K A068820 easy,nonn %O A068820 1,1 %A A068820 _Naohiro Nomoto_, Mar 29 2002