A059266 -id:A059266 - cp's OEIS frontend

A191469 Numbers n such that 7^n - 6 is prime.

2, 3, 6, 9, 21, 25, 33, 49, 54, 133, 245, 255, 318, 1023, 1486, 3334, 6821, 8555, 11605, 42502, 44409, 90291, 92511, 140303

Offset: 1

Vincenzo Librandi, Jun 06 2011

a(14)=1023 and a(15)=1486 correspond to BPSW strong probable primes (passing PARI's ispseudoprime()). - Joerg Arndt, Jun 06 2011

a(25) > 2*10^5. - Robert Price, Nov 14 2014

Cf. A014224, A059266, A059613, A059614, A095714, A177093.

Cf. A236371, A217131, A191469, A090669, A096305, A217130, A217132, A152213.

Magma
```
[n: n in [1..1000]| IsPrime(7^n-6)]
```

A191469:=n->`if`(isprime(7^n-6),n,NULL): seq(A191469(n), n=1..10^3); # Wesley Ivan Hurt, Nov 14 2014

Select[Range[1,5000],PrimeQ[7^#-6]&] (* Vincenzo Librandi, Aug 05 2012 *)

for(n=1, 10^6, if(isprime(7^n-6), print1(n, ", ")))

a(17)-a(23) from Robert Price, Jan 24 2014

a(24) from Robert Price, Nov 14 2014

A135535 Primes of the form 4^k - 3.

Original entry on oeis.org

13, 61, 1021, 4093, 16381, 1048573, 4194301, 16777213, 19807040628566084398385987581, 83076749736557242056487941267521533, 5316911983139663491615228241121378301, 1427247692705959881058285969449495136382746621, 23945242826029513411849172299223580994042798784118781, 118571099379011784113736688648896417641748464297615937576404566024103044751294461, 139984046386112763159840142535527767382602843577165595931249318810236991948760059086304843329475444733

Offset: 1

Daniele Corradetti (d.corradetti(AT)gmail.com), Feb 21 2008

nonn

Involved in the "New Mersenne Prime Conjecture" and in some generalizations of Mersenne primes.

Subsequence of A050415. - Elmo R. Oliveira, Nov 28 2023

			16381 is a term because 4^7 - 3 = 16381 is prime.

Daniel Minoli, Voice over MPLS, McGraw-Hill, New York, NY, 2002, ISBN 0-07-140615-8 (pp. 114-134).

P. T. Bateman, J. L. Selfridge and S. S. Wagstaff, Jr., The New Mersenne Conjecture, Amer. Math. Monthly 96, 125-128, 1989.
D. Minoli and Robert Bear, Hyperperfect Numbers, Pi Mu Epsilon Journal, Fall 1975, pp. 153-157. [Daniel Minoli (daniel.minoli(AT)ses.com), Aug 26 2009]
Daniel Minoli and W. Nakamine, Mersenne Numbers Rooted On 3 For Number Theoretic Transforms, 1980 IEEE International Conf. on Acoust., Speech and Signal Processing. [Daniel Minoli (daniel.minoli(AT)ses.com), Aug 26 2009]
Paul Tannery, Questions 659 et 660, L'Intermédiaire des mathématiciens, Tome II (1895) p. 317.
Eric Weisstein's World of Mathematics, New Mersenne Prime Conjecture

Cf. A000040, A050415, A057732, A057733, A059266.

Do[If[PrimeQ[4^n - 3], Print[4^n - 3]], {n, 100}] (* Robert G. Wilson v, Feb 29 2008 *)
Select[4^Range[200]-3,PrimeQ] (* Harvey P. Dale, Jul 11 2022 *)

a(n) = 4^A059266(n) - 3. - Ryan Propper, Feb 26 2008

More terms from R. J. Mathar, Robert G. Wilson v and Ryan Propper, Feb 26 2008

A164783 a(n) = 7^n-6.

Original entry on oeis.org

1, 43, 337, 2395, 16801, 117643, 823537, 5764795, 40353601, 282475243, 1977326737, 13841287195, 96889010401, 678223072843, 4747561509937, 33232930569595, 232630513987201, 1628413597910443, 11398895185373137

Offset: 1

Daniel Minoli (daniel.minoli(AT)ses.com), Aug 26 2009

Minoli defined the sequences and concepts that follow in the 1980 IEEE paper below: - Sequence m (n,t) = (n^t) - (n-1) for t=2 to infinity is called a Mersenne Sequence Rooted on n - If n is prime, this sequence is called a Legitimate Mersenne Sequence - Any j belonging to the sequence m (n,t) is called a Generalized Mersenne Number (n-GMN) - If j belonging to the sequence m (n,t) is prime, it is then called a n-Generalized Mersenne Prime (n-GMP). Note: m (n,t) = n* m (n,t-1) + n^2 - 2*n+1. This sequence related to sequences: A014232 and A014224; A135535 and A059266. These numbers play a role in the context of hyperperfect numbers.

Daniel Minoli, Sufficient Forms For Generalized Perfect Numbers, Ann. Fac. Sciences, Univ. Nation. Zaire, Section Mathem. Vol. 4, No. 2, Dec 1978, pp. 277-302.
Daniel Minoli, New Results For Hyperperfect Numbers, Abstracts American Math. Soc., October 1980, Issue 6, Vol. 1, pp. 561.
Daniel Minoli, Voice over MPLS, McGraw-Hill, New York, NY, 2002, ISBN 0-07-140615-8 (p.114-134)

Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Daniel Minoli, Issues In Non-Linear Hyperperfect Numbers, Mathematics of Computation, Vol. 34, No. 150, April 1980, pp. 639-645.
D. Minoli, Structural Issues For Hyperperfect Numbers, Fibonacci Quarterly, Feb. 1981, Vol. 19, No. 1, pp. 6-14.
D. Minoli and Robert Bear, Hyperperfect Numbers, Pi Mu Epsilon Journal, Fall 1975, pp. 153-157.
Daniel Minoli and W. Nakamine, Mersenne Numbers Rooted On 3 For Number Theoretic Transforms, 1980 IEEE International Conf. on Acoust., Speech and Signal Processing.
Index entries for linear recurrences with constant coefficients, signature (8,-7).

Cf. A000420.

Cf. A014232, A014224, A135535, A059266.

[7^n-6: n in [1..30]]; // Vincenzo Librandi, Feb 06 2013

CoefficientList[Series[(1 + 35 x)/((1-x) (1-7 x)), {x, 0, 30}], x] (* Vincenzo Librandi, Feb 06 2013 *)
NestList[7 # + 36 & , 1, 18] (* Bruno Berselli, Feb 06 2013 *)
LinearRecurrence[{8,-7},{1,43},30] (* Harvey P. Dale, Nov 27 2014 *)

a(n)=7^n-6 \\ Charles R Greathouse IV, Oct 07 2015

a(n) = 7*a(n-1)+36 with n>1, a(1)=1. - Vincenzo Librandi, Nov 30 2010
G.f.: x*(1+35*x)/((1-x)*(1-7*x)). - Colin Barker, Mar 08 2012
a(n) = 8*a(n-1) - 7*a(n-2) for n>2, a(1)=1, a(2)=43. - Vincenzo Librandi, Feb 06 2013
a(n) = A000420(n) - 6 for n>0. - Michel Marcus, Aug 31 2013

More terms a(8)-a(19) from Vincenzo Librandi, Oct 29 2009

A164784 a(n) = 6^n-5.

Original entry on oeis.org

1, 31, 211, 1291, 7771, 46651, 279931, 1679611, 10077691, 60466171, 362797051, 2176782331, 13060694011, 78364164091, 470184984571, 2821109907451, 16926659444731, 101559956668411, 609359740010491, 3656158440062971

Offset: 1

Daniel Minoli (daniel.minoli(AT)ses.com), Aug 26 2009

Minoli defined the sequences and concepts that follow in the 1980 IEEE paper below: - Sequence m (n,t) = (n^t) - (n-1) for t=2 to infinity is called a Mersenne Sequence Rooted on n - If n is prime, this sequence is called a Legitimate Mersenne Sequence - Any j belonging to the sequence m (n,t) is called a Generalized Mersenne Number (n-GMN) - If j belonging to the sequence m (n,t) is prime, it is then called a n-Generalized Mersenne Prime (n-GMP). Note: m (n,t) = n* m (n,t-1) + n^2 - 2*n+1. This sequence related to sequences: A014232 and A014224; A135535 and A059266. These numbers play a role in the context of hyperperfect numbers. For additional references, beyond key ones listed below, see A164783.

Daniel Minoli, Voice over MPLS, McGraw-Hill, New York, NY, 2002, ISBN 0-07-140615-8 (p.114-134)

Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Daniel Minoli and Robert Bear, Hyperperfect Numbers, Pi Mu Epsilon Journal, Fall 1975, pp. 153-157.
Daniel Minoli, W. Nakamine, Mersenne Numbers Rooted On 3 For Number Theoretic Transforms, 1980 IEEE International Conf. on Acoust., Speech and Signal Processing.
Index entries for linear recurrences with constant coefficients, signature (7, -6).

[6^n-5: n in [1..30]]; // Vincenzo Librandi, Feb 06 2013

CoefficientList[Series[(1 + 24 x)/(1 - 7 x + 6 x^2), {x, 0, 30}],x] (* Vincenzo Librandi, Feb 06 2013 *)

a(n) = 6*a(n-1)+25 with n>1, a(1)=1. - Vincenzo Librandi, Oct 29 2009
G.f.: x*(1 + 24*x)/(1 - 7*x + 6*x^2). - Vincenzo Librandi, Feb 06 2013
E.g.f.: 4 + (exp(5*x) - 5)*exp(x). - Ilya Gutkovskiy, Jun 11 2016

A164785 a(n) = 5^n - 4.

Original entry on oeis.org

1, 21, 121, 621, 3121, 15621, 78121, 390621, 1953121, 9765621, 48828121, 244140621, 1220703121, 6103515621, 30517578121, 152587890621, 762939453121, 3814697265621, 19073486328121, 95367431640621, 476837158203121

Offset: 1

Daniel Minoli (daniel.minoli(AT)ses.com), Aug 26 2009

Minoli defined the sequences and concepts that follow in the 1980 IEEE paper below: - Sequence m(n,t) = (n^t) - (n-1) for t=2 to infinity is called a Mersenne Sequence Rooted on n - If n is prime, this sequence is called a Legitimate Mersenne Sequence - Any j belonging to the sequence m(n,t) is called a Generalized Mersenne Number (n-GMN) - If j belonging to the sequence m (n,t) is prime, it is then called a n-Generalized Mersenne Prime (n-GMP). Note: m (n,t) = n* m (n,t-1) + n^2 - 2*n+1. This sequence related to sequences: A014232 and A014224; A135535 and A059266. These numbers play a role in the context of hyperperfect numbers. For additional references, beyond key ones listed below, see A164783.

Daniel Minoli, Voice over MPLS, McGraw-Hill, New York, NY, 2002, ISBN 0-07-140615-8 (p.114-134)

Harvey P. Dale, Table of n, a(n) for n = 1..1000
Daniel Minoli and W. Nakamine, Mersenne Numbers Rooted On 3 For Number Theoretic Transforms, 1980 IEEE International Conf. on Acoust., Speech and Signal Processing.
Daniel Minoli and Robert Bear, Hyperperfect Numbers, Pi Mu Epsilon Journal, Fall 1975, pp. 153-157.
Index entries for linear recurrences with constant coefficients, signature (6,-5).

Cf. A059613.

[5^n-4: n in [1..30]]; // Vincenzo Librandi, Feb 06 2013

5^Range[50]-4 (* Vladimir Joseph Stephan Orlovsky, Feb 20 2011 *)
LinearRecurrence[{6,-5},{1,21},30] (* or *) NestList[5 # + 16 &, 1, 30] (* Harvey P. Dale, Jun 07 2012 *)
CoefficientList[Series[(1 + 15 x)/(1 - 6 x + 5 x^2), {x, 0, 30}], x] (* Vincenzo Librandi, Feb 06 2013 *)

a(n) = 5*a(n-1) + 16 with n > 1, a(1)=1. - Vincenzo Librandi, Nov 30 2010
a(n) = 6*a(n-1) - 5*a(n-2); a(1)=1, a(2)=21. - Harvey P. Dale, Jun 07 2012
G.f.: x*(1 + 15*x)/(1 - 6*x + 5*x^2). - Vincenzo Librandi, Feb 06 2013
E.g.f.: 3 + (exp(4*x) - 4)*exp(x). - Ilya Gutkovskiy, Jun 11 2016

More terms a(9)-a(21) from Vincenzo Librandi, Oct 29 2009

A164786 a(n) = 8^n-7.

Original entry on oeis.org

1, 57, 505, 4089, 32761, 262137, 2097145, 16777209, 134217721, 1073741817, 8589934585, 68719476729, 549755813881, 4398046511097, 35184372088825, 281474976710649, 2251799813685241, 18014398509481977, 144115188075855865

Offset: 1

Daniel Minoli (daniel.minoli(AT)ses.com), Aug 26 2009

Minoli defined the sequences and concepts that follow in the 1980 IEEE paper below: - Sequence m(n,t) = (n^t) - (n-1) for t=2 to infinity is called a Mersenne Sequence Rooted on n - If n is prime, this sequence is called a Legitimate Mersenne Sequence - Any j belonging to the sequence m(n,t) is called a Generalized Mersenne Number (n-GMN) - If j belonging to the sequence m (n,t) is prime, it is then called a n-Generalized Mersenne Prime (n-GMP). Note: m (n,t) = n* m (n,t-1) + n^2 - 2*n+1. This sequence related to sequences: A014232 and A014224; A135535 and A059266. These numbers play a role in the context of hyperperfect numbers. For additional references, beyond key ones listed below, see A164783.

Daniel Minoli, Voice over MPLS, McGraw-Hill, New York, NY, 2002, ISBN 0-07-140615-8 (p.114-134)

Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Daniel Minoli and Robert Bear, Hyperperfect Numbers, Pi Mu Epsilon Journal, Fall 1975, pp. 153-157.
Daniel Minoli, W. Nakamine, Mersenne Numbers Rooted On 3 For Number Theoretic Transforms, 1980 IEEE International Conf. on Acoust., Speech and Signal Processing.
Index entries for linear recurrences with constant coefficients, signature (9, -8).

[8^n-7: n in [1..20]]; // Vincenzo Librandi, Aug 22 2011

8^Range[20]-7 (* or *) LinearRecurrence[{9,-8},{1,57},20] (* Harvey P. Dale, Jan 24 2013 *)

a(n) = 8*a(n-1)+49, with a(1)=1. - Vincenzo Librandi, Nov 30 2010
G.f.: x*(1+48*x)/(1-9*x+8*x^2). a(n) = 9*a(n-1)-8*a(n-2). - Colin Barker, Jan 28 2012
E.g.f.: 6 + (exp(7*x) - 7)*exp(x). - Ilya Gutkovskiy, Jun 11 2016

More terms a(7)-a(19) from Vincenzo Librandi, Oct 29 2009

A217349 Numbers k such that 4^k + 7 is prime.

Original entry on oeis.org

1, 2, 3, 4, 5, 8, 9, 10, 14, 15, 19, 22, 39, 44, 49, 63, 80, 87, 102, 107, 294, 305, 399, 463, 595, 599, 903, 944, 1324, 1727, 1755, 1932, 1935, 4485, 6165, 6665, 9438, 11169, 19859, 27503, 55392, 86235, 98217, 117855, 123640, 134204, 139660, 150437, 157634, 186475, 236129, 283248, 390142, 410178

Offset: 1

Vincenzo Librandi, Oct 01 2012

nonn

The next terms are > 4.1*10^5. - Elmo R. Oliveira, Nov 29 2023

			For k = 14, 4^14 + 7 = 268435463 is prime.

Cf. A057195, A059266, A089437, A104066 (associated primes).

Select[Range[0, 5000], PrimeQ[4^# + 7] &]

is(n)=ispseudoprime(4^n+7) \\ Charles R Greathouse IV, Jun 06 2017

a(n) = A057195(n)/2.

Extended using A057195 terms by Michel Marcus, Aug 28 2015

a(51)-a(54) derived from A057195 by Elmo R. Oliveira, Nov 29 2023

A217353 Numbers k such that 8^k - 3 is prime.

Original entry on oeis.org

1, 2, 3, 4, 8, 50, 58, 71, 112, 1079, 1318, 2252, 3524, 4800, 5560, 6919, 11484, 12184, 41099, 94711, 375460, 449248

Offset: 1

Vincenzo Librandi, Oct 02 2012

3*A217353 is a subsequence of A050414. - Bruno Berselli, Oct 02 2012

Cf. A050414, A059266, A217354.

Mathematica
```
Select[Range[5000], PrimeQ[8^# - 3] &]
```

is(n)=ispseudoprime(8^n-3) \\ Charles R Greathouse IV, May 22 2017

a(15)-a(17), a(19)-a(20) using A050414 by Bruno Berselli, Oct 02 2012

a(18), a(21)-a(22) using A050414 by Michael S. Branicky, Sep 15 2024

A217348 Numbers k such that 4^k - 5 is prime.

Original entry on oeis.org

2, 3, 4, 5, 6, 9, 10, 13, 16, 18, 28, 33, 59, 65, 75, 83, 103, 113, 275, 353, 405, 568, 614, 909, 1184, 1200, 1564, 2266, 2556, 4246, 8014, 8193, 8696, 9291, 10993, 12146, 13809, 15459, 16381, 24106, 60220, 91816, 158070, 182491, 207016, 266675, 297561

Offset: 1

Vincenzo Librandi, Oct 01 2012

			28 is a term because 4^28 - 5 = 72057594037927931 is prime.

Cf. A059266, A059608, A059614.

Mathematica
```
Select[Range[10000], PrimeQ[4^# - 5] &]
```

/* Up to 620 the code produces in few seconds the first terms: */
allocatemem(10000000); for(n=2, 620, if(isprime(4^n-5), print1(n", ")));

a(n) = A059608(n+1)/2. - Daniel Starodubtsev, Mar 20 2020

a(31)-a(34) from Bruno Berselli, Oct 02 2012
a(35)-a(45) from Daniel Starodubtsev, Mar 20 2020
a(46)-a(47) derived from A059608 by Elmo R. Oliveira, Nov 28 2023

A305531 Smallest k >= 1 such that (n-1)*n^k + 1 is prime.

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 2, 1, 3, 10, 3, 1, 2, 1, 1, 4, 1, 29, 14, 1, 1, 14, 2, 1, 2, 4, 1, 2, 4, 5, 12, 2, 1, 2, 2, 9, 16, 1, 2, 80, 1, 2, 4, 2, 3, 16, 2, 2, 2, 1, 15, 960, 15, 1, 4, 3, 1, 14, 1, 6, 20, 1, 3, 946, 6, 1, 18, 10, 1, 4, 1, 5, 42, 4, 1, 828, 1, 1, 2, 1, 12, 2, 6, 4, 30, 3, 3022, 2, 1, 1

Offset: 2

Eric Chen, Jun 04 2018

nonn

a(prime(j)) + 1 = A087139(j).
a(123) > 10^5, a(342) > 10^5, see the Barnes link for the Sierpinski base-123 and base-342 problems.
a(251) > 73000, see A087139.

Eric Chen, Table of n, a(n) for n = 2..122
Gary Barnes, Sierpinski conjectures and proofs
Eric Chen, Table n, a(n) for n = 2..360 status

For the numbers k such that these forms are prime:
a1(b): numbers k such that (b-1)*b^k-1 is prime
a2(b): numbers k such that (b-1)*b^k+1 is prime
a3(b): numbers k such that (b+1)*b^k-1 is prime
a4(b): numbers k such that (b+1)*b^k+1 is prime (no such k exists when b == 1 (mod 3))
a5(b): numbers k such that b^k-(b-1) is prime
a6(b): numbers k such that b^k+(b-1) is prime
a7(b): numbers k such that b^k-(b+1) is prime
a8(b): numbers k such that b^k+(b+1) is prime (no such k exists when b == 1 (mod 3)).
Using "-------" if there is currently no OEIS sequence and "xxxxxxx" if no such k exists (this occurs only for a4(b) and a8(b) for b == 1 (mod 3)):
.
   b   a1(b)   a2(b)   a3(b)   a4(b)   a5(b)   a6(b)   a7(b)   a8(b)
--------------------------------------------------------------------
   2 A000043 ------- A002235 A002253 A000043 ------- A050414 A057732
   3 A003307 A003306 A005540 A005537 A014224 A051783 A058959 A058958
   4 A272057 ------- ------- xxxxxxx A059266 A089437 A217348 xxxxxxx
   5 A046865 A204322 A257790 A143279 A059613 A124621 A165701 A089142
   6 A079906 A247260 ------- ------- A059614 A145106 A217352 A217351
   7 A046866 A245241 ------- xxxxxxx A191469 A217130 A217131 xxxxxxx
   8 A268061 A269544 ------- ------- A217380 A217381 A217383 A217382
   9 A268356 A056799 ------- ------- A177093 A217385 A217493 A217492
  10 A056725 A056797 A111391 xxxxxxx A095714 A088275 A092767 xxxxxxx
  11 A046867 A057462 ------- ------- ------- ------- ------- -------
  12 A079907 A251259 ------- ------- ------- A137654 ------- -------
  13 A297348 ------- ------- xxxxxxx ------- ------- ------- xxxxxxx
  14 A273523 ------- ------- ------- ------- ------- ------- -------
  15 ------- ------- ------- ------- ------- ------- ------- -------
  16 ------- ------- ------- xxxxxxx ------- ------- ------- xxxxxxx
Cf. (smallest k such that these forms are prime) A122396 (a1(b)+1 for prime b), A087139 (a2(b)+1 for prime b), A113516 (a5(b)), A076845 (a6(b)), A178250 (a7(b)).

a(n)=for(k=1,2^16,if(ispseudoprime((n-1)*n^k+1),return(k)))

cp's OEIS Frontend

A191469 Numbers n such that 7^n - 6 is prime.

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A135535 Primes of the form 4^k - 3.

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A164783 a(n) = 7^n-6.

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Magma

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PARI

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A164784 a(n) = 6^n-5.

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Magma

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Formula

A164785 a(n) = 5^n - 4.

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Crossrefs

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Magma

Mathematica

Formula

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A164786 a(n) = 8^n-7.

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References

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Programs

Magma

Mathematica

Formula

Extensions

A217349 Numbers k such that 4^k + 7 is prime.

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Keywords