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.
Gilbert Mozzo has authored 16 sequences. Here are the ten most recent ones:
17 = 6*Fibonacci(4) - 1 = 6*3 - 1.
Select[6*Fibonacci[Range[2,500]]-1,AllTrue[#+{0,2},PrimeQ]&] (* Harvey P. Dale, Apr 18 2025 *)
for (n=2, 1000, if (ispseudoprime (p=6*fibonacci(n)-1) && ispseudoprime (p+2), print1(p", ")))
Select[3*2^Range[4,100]-25 , PrimeQ] (* Amiram Eldar, Nov 15 2018 *)
for(n=0,20, if(ispseudoprime(p=3*2^n-25), print1(p, ", ")))
7 is a term, because 3*2^7 - 25 = 359 is prime.
Select[Range[100], PrimeQ[3 2^# - 25] &]
for(n=0, 2000, if(ispseudoprime(p=3*2^n-25), print1(n, ", ")));
For Mersenne 5, i.e., 8191, the first computed prefix is equal to 1 and gives 18191 which is also a prime, so a(5) = 1.
pfx[n_] := Module[{w = 10^(1+Floor[Log10[n]])}, k=n+w ; While[!PrimeQ[k], k+=w]; Floor[k/w]]; s={}; Do[m = 2^MersennePrimeExponent[n]-1; AppendTo[s, pfx[m]], {n, 1, 12}]; s (* Amiram Eldar, Nov 22 2018 based on Andrew Howroyd's pari code *)
pfx(n)={my(w=10^(1+logint(n,10)), k=n+w); while(!ispseudoprime(k), k+=w); k\w}
{ for(n=1, 500, my(p=1<Andrew Howroyd, Nov 17 2018
For Mersenne4: -1 + 2^7 + 4*10^3 = 4127 which is prime.
ppfx(n)={my(w=10^(1+logint(n,10)), k=n+w); while(!ispseudoprime(k), k+=w); k}
{ for(n=1, 100, my(p=1<Andrew Howroyd, Nov 17 2018
a(4) = 5 because (6^5-11)/5 = 1553 is prime.
lst={}; Do[If[PrimeQ[(6^n-11)/5], Print[n]; AppendTo[lst, n]], {n, 10^6}]; lst
is(n)=ispseudoprime((6^n-11)/5) \\ Charles R Greathouse IV, Jun 13 2017
(6^4-11)/5=257, which is in the sequence because it is prime.
[(6^n-11)/5: n in [1..10^3] | IsPrime((6^n-11) div 5)];
lst={}; Do[If[PrimeQ[(6^n-11)/5], Print[(6^n-11)/5]; AppendTo[lst, (6^n-11)/5]], {n, 10^6}];
for(n=1,1e4,if(ispseudoprime(t=6^n\5-2),print1(t", "))) \\ Charles R Greathouse IV, Nov 01 2011
17*6^13-1 and 17*6^13+1 are twins.
maxM = 5; r = Select[Prime[Range[PrimePi[2*6^maxM]]], PrimeQ[# + 2] &] + 1; u = Sort[Flatten[Table[Select[r,PrimeQ[#/6^k] &] - 1, {k, maxM}]]]; Sort[Join[u, u + 2]] (* T. D. Noe, Feb 28 2011 *)
5*6^1-1 = 29 is prime and therefore a term. 7*6^2-1 = 251 is prime and therefore a term. 17*6^13-1 = 222031798271 is prime and therefore a term (see also its companion in A185069).
IsA186782:=function(n); k:=n+1; while k mod 6 eq 0 do k:=(k div 6); end while; return IsPrime(k); end function; [ n: n in PrimesUpTo(3000) | IsA186782(n) ]; // Klaus Brockhaus, Mar 01 2011
maxM = 4; p = Prime[Range[PrimePi[2*6^maxM]]];Sort[Flatten[Table[Select[p + 1, PrimeQ[#/6^k] &], {k, 0, maxM}] - 1]] (* T. D. Noe, Feb 28 2011 *)
(2^1279-1)*6^1047-1 is prime.
[n: n in [0..3000] | IsPrime((2^1279-1)*6^n-1)];
Union[Flatten[Table[Select[p*6^Range[0, 30] - 1, # < 10^20 && PrimeQ[#] &], {p, {3, 7, 31, 127, 8191, 131071, 524287, 2147483647, 2305843009213693951}}]]]
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