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.
Select[ Prime[ Range[1, 100000] ], PrimeQ[ (10^# + 9^#)/19 ]& ]
is(n)=isprime((10^n+9^n)/19) \\ Charles R Greathouse IV, Feb 17 2017
Select[ Prime[ Range[1, 100000] ], PrimeQ[ (12^# + 11^#)/23 ]& ]
is(n)=ispseudoprime((12^n+11^n)/23) \\ Charles R Greathouse IV, Feb 20 2017
Select[ Prime[ Range[1, 100000] ], PrimeQ[ (15^# + 14^#)/29 ]& ]
is(n)=ispseudoprime((15^n+14^n)/29) \\ Charles R Greathouse IV, Feb 20 2017
Select[ Prime[ Range[1, 100000] ], PrimeQ[ (11^# + 10^#)/21 ]& ]
is(n)=ispseudoprime((11^n+10^n)/21) \\ Charles R Greathouse IV, May 22 2017
is(n)=ispseudoprime((16^n+15^n)/31) \\ Charles R Greathouse IV, May 22 2017
Select[ Prime[ Range[1, 100000] ], PrimeQ[ (11^# + 4^#)/15 ]& ]
is(n)=ispseudoprime((11^n+4^n)/15) \\ Charles R Greathouse IV, Jun 06 2017
Select[ Prime[ Range[1, 100000] ], PrimeQ[ (14^# + 13^#)/27 ]& ]
forprime(p=3,10^6, if(ispseudoprime((14^p + 13^p)/27), print1(p,", ") ) ); \\ Joerg Arndt, Jul 29 2013
a(10) = 53 because (10^p + 11^p)/21 is composite for all p < 53 and prime for p = 53.
lmt = 4200; f[n_] := Block[{p = 2}, While[p < lmt && !PrimeQ[((n + 1)^p + n^p)/(2n + 1)], p = NextPrime@ p]; If[p > lmt, 0, p]]; Do[Print[{n, f[n] // Timing}], {n, 1000}] (* Robert G. Wilson v, Dec 01 2014 *)
a(n)=forprime(p=3, , if(ispseudoprime((n^p+(n+1)^p)/(2*n+1)), return(p)))
is(n)=ispseudoprime((18^n+17^n)/35) \\ Charles R Greathouse IV, Jun 13 2017
Select[ Prime[ Range[1, 100000] ], PrimeQ[ (9^# + 4^#)/13 ]& ]
is(n)=ispseudoprime((9^n+4^n)/13) \\ Charles R Greathouse IV, Jun 13 2017
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