cp's OEIS Frontend

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.

Showing 1-7 of 7 results.

A155845 Primes of the form 2^p-p*q where p is prime,q=3.

Original entry on oeis.org

-2, 17, 107, 524231, 8388539, 162259276829213363391578010287807
Offset: 1

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Author

Keywords

Comments

The next term has 1342 digits. - Harvey P. Dale, Dec 09 2013

Crossrefs

Programs

  • Mathematica
    q=3;lst={};Do[p=Prime[n];If[PrimeQ[p=2^p-p*q],AppendTo[lst,p]],{n,5!}];lst
    Select[2^#-3#&/@Prime[Range[900]],PrimeQ] (* Harvey P. Dale, Dec 09 2013 *)

A155846 Primes of the form 2^p-p*q where p is prime,q=5.

Original entry on oeis.org

-7, 7, 1993, 130987, 536870767, 9007199254740727
Offset: 1

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Keywords

Crossrefs

Programs

  • Mathematica
    q=5;lst={};Do[p=Prime[n];If[PrimeQ[p=2^p-p*q],AppendTo[lst,p]],{n,5!}];lst
    Select[Table[2^p-5p,{p,Prime[Range[50]]}],PrimeQ] (* Harvey P. Dale, Jul 02 2018 *)

A155847 Primes of the form 2^p-p*q where p is prime,q=7.

Original entry on oeis.org

-13, -3, 79, 8101
Offset: 1

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Author

Keywords

Crossrefs

Programs

  • Mathematica
    q=7;lst={};Do[p=Prime[n];If[PrimeQ[p=2^p-p*q],AppendTo[lst,p]],{n,5!}];lst

A358087 Primes that can be written as 2^x - p where p is a prime and x is a multiple of p.

Original entry on oeis.org

2, 5, 61, 509, 1019, 4093, 8179, 524269, 1048571, 16777213, 2596148429267413814265248164610011, 1361129467683753853853498429727072845819, 1427247692705959881058285969449495136382746619, 1427247692705959881058285969449495136382746621, 45671926166590716193865151022383844364247891937
Offset: 1

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Author

J. M. Bergot and Robert Israel, Oct 30 2022

Keywords

Examples

			a(3) = 61 is a term because 61 = 2^6 - 3 where 61 and 3 are prime and 6 is divisible by 3.
		

Crossrefs

Contains A057678.
Cf. A358079.

Programs

  • Maple
    R:= NULL: count:= 0:
    for k from 1 while count < 20 do
      P:= sort(convert(numtheory:-factorset(k),list),`>`);
      for p in P do
        x:= 2^k-p;
        if isprime(x) then R:= R,x; count:= count+1; fi
    od od:
    R;

A182474 Primes of the form p^q - q, where p and q are primes.

Original entry on oeis.org

2, 5, 7, 23, 47, 167, 359, 839, 1367, 1847, 2207, 3719, 5039, 7919, 8179, 10607, 11447, 16127, 17159, 19319, 29927, 36479, 44519, 49727, 54287, 57119, 66047, 85847, 97967, 113567, 128879, 177239, 196247, 201599, 218087, 241079, 273527, 292679, 323759, 344567
Offset: 1

Views

Author

Alex Ratushnyak, May 01 2012

Keywords

Examples

			8179 = 2^13 - 13
		

Crossrefs

Cf. A049002 (primes of the form p^2 - 2).
Cf. A057678 (primes of the form 2^p - p).

Programs

  • Mathematica
    nn = 600000; mx = Floor[Log[2, nn]]; t2 = Select[Table[2^n - n, {n, Prime[Range[PrimePi[mx]]]}], PrimeQ]; mx = Floor[Sqrt[nn]]; tp = Select[Table[n^2 - 2, {n, Prime[Range[PrimePi[mx]]]}], PrimeQ]; Union[t2, tp] (* T. D. Noe, May 01 2012 *)
    Module[{upto=350000,r},r=Floor[Sqrt[upto+2]];Select[Union[Select[ (#1[[1]]^#1[[2]]-#1[[2]]&)/@Tuples[Prime[Range[r]],2], PrimeQ]], #1<=upto&]] (* Harvey P. Dale, Dec 07 2012 *)

Formula

Union of A049002 and A057678.

A155848 Primes of the form 2^p-p*q where p is prime, q=9.

Original entry on oeis.org

-19, -13, 1949, 2535301200456458802993406409843
Offset: 1

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Author

Keywords

Crossrefs

Programs

  • Mathematica
    q=9;lst={};Do[p=Prime[n];If[PrimeQ[p=2^p-p*q],AppendTo[lst,p]],{n,5!}];lst
    Select[2^#-9#&/@Prime[Range[50]],PrimeQ] (* Harvey P. Dale, Aug 26 2014 *)

A155849 Primes of the form 2^p-p*q where p is prime,q=15.

Original entry on oeis.org

-37, -43, 23, 130817, 2535301200456458802993406409237, 36499524940977561749129372845602330599145828057988479444633540143194201337669419092047302490538971198229138476588755258485509637771003503986021290557777713506015957394882119600662993537972820563
Offset: 1

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Author

Keywords

Crossrefs

Programs

  • Mathematica
    q=15;lst={};Do[p=Prime[n];If[PrimeQ[p=2^p-p*q],AppendTo[lst,p]],{n,5!}];lst
Showing 1-7 of 7 results.