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[(11^# - 4^#)/7]&]
is(n)=ispseudoprime((11^n-4^n)/7) \\ Charles R Greathouse IV, Feb 20 2017
Do[f=5^n+3^n;If[PrimeQ[f/2^3],Print[{n,f/2^3}]],{n,1,1231}] (* Alexander Adamchuk, Sep 14 2006 *)
s={};Do[k=1;Until[PrimeQ[((2n+1)^k-(2n-1)^k)/2],k++];AppendTo[s,k] ,{n,35}];s (* James C. McMahon, Oct 27 2024 *)
Do[If[PrimeQ[(5^Prime[n] - 3^Prime[n])/2], Print[n]], {n, 1000}] (* Robert G. Wilson v, Jan 12 2007 *)
PrimePi[#]&/@Select[Prime[Range[1000]],PrimeQ[(5^#-3^#)/2]&] (* Harvey P. Dale, Sep 23 2018 *)
Select[ Prime[ Range[1, 100000] ], PrimeQ[ (9^# - 2^#)/7 ]& ]
is(n)=ispseudoprime((9^n-2^n)/7) \\ Charles R Greathouse IV, Jun 06 2017
a(n) = my(p=2); if(n%3, while(!ispseudoprime(((n+3)^p-3^p)/n), p=nextprime(p+1)); p, 0); \\ Jinyuan Wang, Nov 28 2020
Select[ Prime[ Range[1, 300] ], PrimeQ[ (7^# - 2^#)/5 ]& ]
is(n)=ispseudoprime((7^n-2^n)/5) \\ Charles R Greathouse IV, Jun 13 2017
Select[Prime[Range[1, 100000]], PrimeQ[(13^# - 4^#)/9]&]
is(n)=ispseudoprime((13^n-4^n)/9) \\ Charles R Greathouse IV, Jun 13 2017
Read by rows: m\n 1 2 3 4 5 6 7 8 9 10 11 2 3 3 3 3 4 0 0 3 5 3 5 13 3 6 3 0 0 0 5 7 5 3 3 5 3 3 8 3 0 3 0 19 0 7 9 0 3 0 0 3 0 3 7 10 19 0 3 0 0 0 31 0 3 11 17 5 3 3 5 3 5 7 5 3 12 3 0 0 0 3 0 3 0 0 0 3 etc.
t1[n_] := Floor[3/2 + Sqrt[2*n]]
m[n_] := Floor[(-1 + Sqrt[8*n-7])/2]
t2[n_] := n-m[n]*(m[n]+1)/2
b[n_] := GCD @@ Last /@ FactorInteger[n]
is[m_, n_] := GCD[m, n] == 1 && GCD[b[m], b[n]] == 1
Do[k=2, If[is[t1[n], t2[n]], While[ !PrimeQ[t1[n]^Prime[k] - t2[n]^Prime[k]], k++]; Print[Prime[k]], Print[0]], {n, 1, 663}] (* Eric Chen, Jun 01 2015 *)
a052409(n) = my(k=ispower(n)); if(k, k, n>1);
a(m, n) = {if (gcd(m,n) != 1, return (0)); if (gcd(a052409(m), a052409(n)) != 1, return (0)); forprime(p=3,, if (isprime((m^p-n^p)/(m-n)), return (p)););}
tabl(nn) = {for (m=2, nn, for(n=1, m-1, print1(a(m,n), ", ");); print(););} \\ Michel Marcus, Nov 19 2014
t1(n)=floor(3/2+sqrt(2*n)) t2(n)=n-binomial(floor(1/2+sqrt(2*n)), 2) b(n)=my(k=ispower(n)); if(k, k, n>1) a(n)=if(gcd(t1(n),t2(n)) !=1 || gcd(b(t1(n)), b(t2(n))) !=1, 0, forprime(p=3,2^24,if(ispseudoprime((t1(n)^p-t2(n)^p)/(t1(n)-t2(n))), return(p)))) \\ Eric Chen, Jun 01 2015
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