A152585
Generalized Fermat numbers: 12^(2^n) + 1, n >= 0.
Original entry on oeis.org
13, 145, 20737, 429981697, 184884258895036417, 34182189187166852111368841966125057, 1168422057627266461843148138873451659428421700563161428957815831003137
Offset: 0
a(0) = 12^1+1 = 13 = 11(1)+2 = 11(empty product)+2.
a(1) = 12^2+1 = 145 = 11(13)+2.
a(2) = 12^4+1 = 20737 = 11(13*145)+2.
a(3) = 12^8+1 = 429981697 = 11(13*145*20737)+2.
a(4) = 12^16+1 = 184884258895036417 = 11(13*145*20737*429981697)+2.
a(5) = 12^32+1 = 34182189187166852111368841966125057 = 11(13*145*20737*429981697*184884258895036417)+2.
- Vincenzo Librandi, Table of n, a(n) for n = 0..12
- Anders Björn and Hans Riesel, Factors of Generalized Fermat Numbers, Mathematics of Computation, Vol. 67, No. 221, Jan., 1998, pp. 441-446.
- C. K. Caldwell, "Top Twenty" page, Generalized Fermat Divisors (base=12).
- Wilfrid Keller, GFN12 factoring status.
- Eric Weisstein's World of Mathematics, Generalized Fermat Number.
- OEIS Wiki, Generalized Fermat numbers.
Cf.
A000215 (Fermat numbers: 2^(2^n)+1, n >= 0).
-
[12^(2^n) + 1: n in [0..8]]; // Vincenzo Librandi, Jun 20 2011
-
Table[12^2^n + 1, {n, 0, 6}] (* Arkadiusz Wesolowski, Nov 02 2012 *)
-
g(a,n) = if(a%2,b=2,b=1);for(x=0,n,y=a^(2^x)+b;print1(y","))
-
def A152585(n): return (1<<2*(m:=1<Chai Wah Wu, Jul 19 2022
A035089
Smallest prime of form 2^n*k + 1.
Original entry on oeis.org
2, 3, 5, 17, 17, 97, 193, 257, 257, 7681, 12289, 12289, 12289, 40961, 65537, 65537, 65537, 786433, 786433, 5767169, 7340033, 23068673, 104857601, 167772161, 167772161, 167772161, 469762049, 2013265921, 3221225473, 3221225473, 3221225473, 75161927681
Offset: 0
Cf.
A007522,
A057775,
A127575,
A127576,
A127577,
A127578,
A127580,
A127581,
A087522,
A127586,
A127587.
-
a = {}; Do[k = 0; While[ !PrimeQ[k 2^n + 1], k++ ]; AppendTo[a, k 2^n + 1], {n, 1, 50}]; a (* Artur Jasinski *)
-
a(n)=for(k=1,9e99,if(ispseudoprime(k<Charles R Greathouse IV, Jul 06 2011
A000289
A nonlinear recurrence: a(n) = a(n-1)^2 - 3*a(n-1) + 3 (for n>1).
Original entry on oeis.org
1, 4, 7, 31, 871, 756031, 571580604871, 326704387862983487112031, 106735757048926752040856495274871386126283608871, 11392521832807516835658052968328096177131218666695418950023483907701862019030266123104859068031
Offset: 0
- N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
- N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
- John Cerkan, Table of n, a(n) for n = 0..12
- A. V. Aho and N. J. A. Sloane, Some doubly exponential sequences, Fibonacci Quarterly, Vol. 11, No. 4 (1973), pp. 429-437.
- A. V. Aho and N. J. A. Sloane, Some doubly exponential sequences, Fibonacci Quarterly, Vol. 11, No. 4 (1973), pp. 429-437 (original plus references that F.Q. forgot to include - see last page!)
- S. W. Golomb, On certain nonlinear recurring sequences, Amer. Math. Monthly 70 (1963), 403-405.
- Romeo Meštrović, Euclid's theorem on the infinitude of primes: a historical survey of its proofs (300 BC--2012) and another new proof, arXiv preprint arXiv:1202.3670 [math.HO], 2012. - _N. J. A. Sloane_, Jun 13 2012
- Seppo Mustonen, On integer sequences with mutual k-residues
- Seppo Mustonen, On integer sequences with mutual k-residues [Local copy]
- Index entries for sequences of form a(n+1)=a(n)^2 + ...
-
Join[{1}, RecurrenceTable[{a[n] == a[n-1]^2 - 3*a[n-1] + 3, a[1] == 4}, a, {n, 1, 9}]] (* Jean-François Alcover, Feb 06 2016 *)
-
a(n)=if(n<2,max(0,1+3*n),a(n-1)^2-3*a(n-1)+3)
A050922
Triangle in which n-th row gives prime factors of n-th Fermat number 2^(2^n)+1.
Original entry on oeis.org
3, 5, 17, 257, 65537, 641, 6700417, 274177, 67280421310721, 59649589127497217, 5704689200685129054721, 1238926361552897, 93461639715357977769163558199606896584051237541638188580280321
Offset: 0
Triangle begins:
3;
5;
17;
257;
65537;
641, 6700417;
274177, 67280421310721;
59649589127497217, 5704689200685129054721;
1238926361552897, 93461639715357977769163558199606896584051237541638188580280321;
...
A001317(127) = 3*5*17*257*65537.641*6700417*274177*6728042130721, A001317(128) = 59649589127497217*5704689200685129054721. See also A050922. Compare with A053576, where 2 and A000215 appear as prime factors. - _Labos Elemer_, Jan 21 2002
- M. Aigner and G. M. Ziegler, Proofs from The Book, Springer-Verlag, Berlin, 2nd. ed., 2001; see p. 3.
- Jeppe Stig Nielsen, Table of n, a(n) for n = 0..29
- J. Bernheiden, Fermat Numbers (Text in German)
- R. P. Brent, Factorization of the tenth Fermat number
- R. P. Brent, Factorization of the eleventh Fermat number
- R. P. Brent, Succinct proofs of primality for the factors of some Fermat numbers
- R. P. Brent & J. M. Pollard, Factorization of the eighth Fermat number
- R. P. Brent et al., Three new factors of Fermat numbers
- C. K. Caldwell, The Prime Glossary, Fermat divisor
- Wilfrid Keller, Prime factors k.2^n + 1 of Fermat numbers F_m
- R. Mestrovic, Euclid's theorem on the infinitude of primes: a historical survey of its proofs (300 BC--2012) and another new proof, arXiv preprint arXiv:1202.3670, 2012. - From _N. J. A. Sloane_, Jun 13 2012
- R. Munafo, Notes on Fermat numbers
- Mercedes Orús-Lacort, Fermat numbers are not prime numbers for n >= 5, (2020).
- Eric Weisstein's World of Mathematics, Fermat Number
-
Flatten[Transpose[FactorInteger[#]][[1]]&/@Table[2^(2^n)+1,{n,0,8}]] (* Harvey P. Dale, May 18 2012 *)
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for(n=0, 1e3, f=factor(2^(2^n)+1)[, 1]; for(i=1, #f, print1(f[i], ", "))) \\ Felix Fröhlich, Aug 16 2014
More terms from Larry Reeves (larryr(AT)acm.org), Apr 13 2000.
A121270
Prime Sierpinski numbers of the first kind: primes of the form k^k+1.
Original entry on oeis.org
- See e.g. pp. 156-157 in M. Krizek, F. Luca & L. Somer, 17 Lectures on Fermat Numbers, Springer-Verlag NY 2001. - Walter Nissen, Mar 20 2010
-
Do[f=n^n+1;If[PrimeQ[f],Print[{n,f}]],{n,1,1000}]
-
for(n=1,9,if(ispseudoprime(t=n^n+1),print1(t", "))) \\ Charles R Greathouse IV, Feb 01 2013
A090872
a(n) is the smallest number m greater than 1 such that m^(2^k)+1 for k=0,1,...,n are primes.
Original entry on oeis.org
2, 2, 2, 2, 2, 7072833120, 2072005925466, 240164550712338756
Offset: 0
a(5)=7072833120 because 7072833120^2^k+1 for k=0,1,2,3,4,5 are primes.
A000324
A nonlinear recurrence: a(0) = 1, a(1) = 5, a(n) = a(n-1)^2 - 4*a(n-1) + 4 for n>1.
Original entry on oeis.org
1, 5, 9, 49, 2209, 4870849, 23725150497409, 562882766124611619513723649, 316837008400094222150776738483768236006420971486980609
Offset: 0
- Derek Jennings, Some reciprocal summation identities with applications to the Fibonacci and Lucas numbers, in: G. E. Bergum, Applications of Fibonacci Numbers, Vol. 7, Bergum G. E. et al. (eds.), Kluwer Academic Publishers, 1998, pp. 197-200.
- N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
- N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
- T. D. Noe, Table of n, a(n) for n = 0..12
- A. V. Aho and N. J. A. Sloane, Some doubly exponential sequences, Fibonacci Quarterly, Vol. 11, No. 4 (1973), pp. 429-437.
- A. V. Aho and N. J. A. Sloane, Some doubly exponential sequences, Fibonacci Quarterly, Vol. 11, No. 4 (1973), pp. 429-437 (original plus references that F.Q. forgot to include - see last page!)
- Daniel Duverney, Irrationality of Fast Converging Series of Rational Numbers, Journal of Mathematical Sciences-University of Tokyo, Vol. 8, No. 2 (2001), pp. 275-316.
- Daniel Duverney and Takeshi Kurosawa, Transcendence of infinite products involving Fibonacci and Lucas numbers, Research in Number Theory, Vol. 8 (2002), Article 68.
- Solomon W. Golomb, On certain nonlinear recurring sequences, Amer. Math. Monthly, Vol. 70, No. 4 (1963), 403-405.
- Romeo Meštrović, Euclid's theorem on the infinitude of primes: a historical survey of its proofs (300 BC--2012) and another new proof, arXiv preprint arXiv:1202.3670 [math.HO], 2012. - _N. J. A. Sloane_, Jun 13 2012
- Seppo Mustonen, On integer sequences with mutual k-residues, 2005.
- Seppo Mustonen, On integer sequences with mutual k-residues, 2005. [Local copy]
- Index entries for sequences of form a(n+1)=a(n)^2 + ....
-
t = {1, 5}; Do[AppendTo[t, t[[-1]]^2 - 4*t[[-1]] + 4], {n, 11}] (* T. D. Noe, Jun 19 2012 *)
Join[{1}, RecurrenceTable[{a[n] == a[n-1]^2 - 4*a[n-1] + 4, a[1] == 5}, a, {n, 1, 8}]] (* Jean-François Alcover, Feb 07 2016 *)
Join[{1},NestList[#^2-4#+4&,5,10]] (* Harvey P. Dale, Dec 11 2023 *)
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a(n)=if(n<2,max(0,1+4*n),a(n-1)^2-4*a(n-1)+4)
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a(n)=if(n<1,n==0,n=2^n;fibonacci(n+1)+fibonacci(n-1)+2)
A152581
Generalized Fermat numbers: a(n) = 8^(2^n) + 1, n >= 0.
Original entry on oeis.org
9, 65, 4097, 16777217, 281474976710657, 79228162514264337593543950337, 6277101735386680763835789423207666416102355444464034512897
Offset: 0
For n = 3, 8^(2^3) + 1 = 16777217. Similarly, (2^8)^3 + 1 = 16777217. Then 2^8 + 1 = 257 and 16777217/257 = 65281.
- Charles R Greathouse IV, Table of n, a(n) for n = 0..10
- Anders Björn and Hans Riesel, Factors of Generalized Fermat Numbers, Mathematics of Computation, Vol. 67, No. 221, Jan., 1998, pp. 441-446.
- Eric Weisstein's World of Mathematics, Generalized Fermat Number.
- OEIS Wiki, Generalized Fermat numbers.
Cf.
A000215 (Fermat numbers: 2^(2^n) + 1, n >= 0).
-
[8^(2^n) + 1: n in [0..8]]; // Vincenzo Librandi, Jun 20 2011
-
Table[8^2^n + 1, {n, 0, 6}] (* Arkadiusz Wesolowski, Nov 02 2012 *)
-
g(a,n) = if(a%2,b=2,b=1);for(x=0,n,y=a^(2^x)+b;print1(y","))
-
a(n)=1<<(3*2^n)+1 \\ Charles R Greathouse IV, Jul 29 2011
A177888
P_n(k) with P_0(z) = z+1 and P_n(z) = z + P_(n-1)(z)*(P_(n-1)(z)-z) for n>1; square array P_n(k), n>=0, k>=0, read by antidiagonals.
Original entry on oeis.org
1, 2, 1, 3, 3, 1, 4, 5, 7, 1, 5, 7, 17, 43, 1, 6, 9, 31, 257, 1807, 1, 7, 11, 49, 871, 65537, 3263443, 1, 8, 13, 71, 2209, 756031, 4294967297, 10650056950807, 1, 9, 15, 97, 4691, 4870849, 571580604871, 18446744073709551617, 113423713055421844361000443, 1
Offset: 0
Square array P_n(k) begins:
1, 2, 3, 4, 5, 6, 7, 8, ...
1, 3, 5, 7, 9, 11, 13, 15, ...
1, 7, 17, 31, 49, 71, 97, 127, ...
1, 43, 257, 871, 2209, 4691, 8833, 15247, ...
1, 1807, 65537, 756031, 4870849, ...
1, 3263443, 4294967297, ...
1, 10650056950807, ...
- Alois P. Heinz, Antidiagonals n = 0..13, flattened
- A. V. Aho and N. J. A. Sloane, Some doubly exponential sequences, Fibonacci Quarterly, Vol. 11, No. 4 (1973), pp. 429-437.
- A. V. Aho and N. J. A. Sloane, Some doubly exponential sequences, Fibonacci Quarterly, Vol. 11, No. 4 (1973), pp. 429-437 (original plus references that F.Q. forgot to include - see last page!)
Columns k=0-10 give:
A000012,
A000058(n+1),
A000215,
A000289(n+1),
A000324(n+1),
A001543(n+1),
A001544(n+1),
A067686,
A110360(n+1),
A110368(n+1),
A110383(n+1).
Coefficients of P_n(z) give:
A177701.
-
p:= proc(n) option remember;
z-> z+ `if`(n=0, 1, p(n-1)(z)*(p(n-1)(z)-z))
end:
seq(seq(p(n)(d-n), n=0..d), d=0..8);
-
p[n_] := p[n] = Function[z, z + If [n == 0, 1, p[n-1][z]*(p[n-1][z]-z)] ]; Table [Table[p[n][d-n], {n, 0, d}], {d, 0, 8}] // Flatten (* Jean-François Alcover, Dec 13 2013, translated from Maple *)
A046052
Number of prime factors of Fermat number F(n).
Original entry on oeis.org
1, 1, 1, 1, 1, 2, 2, 2, 2, 3, 4, 5
Offset: 0
Comments