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 1-10 of 10 results.

A160491 First differences of A062481.

Original entry on oeis.org

7, 235, 16141, 48811741, 13011865891, 232617453293191, 143882557561868665, 8862794004464425240057, 99999991137061880347498904071, 191843424957750480504146841291811
Offset: 1

Views

Author

Cino Hilliard, May 15 2009

Keywords

Comments

a(1), a(3) and a(6) are the only primes found for n up to 10000 using The C/Gmp program in the link which is 17 times faster than the PARI routine. We read large blocks of primes into memory and test in memory.
If another prime exists, it is larger than 418977 digits.
A concept of order can be introduced here by researching and analyzing the next-nextprime, next-next-nextprime etc.

Examples

			For n = 3, 4^7 - 3^3 = 16141, the 3rd entry in the sequence.
		

Programs

  • PARI
    ppower(n) = { for(x=1,n, y=(x+1)^prime(x+1)-x^prime(x); print1(y",") ); }

Formula

a(n) = A062481(n+1) - A062481(n).

Extensions

Edited by R. J. Mathar, May 17 2009

A123113 Main diagonal of prime power sum array.

Original entry on oeis.org

2, 13, 280, 17489, 48909526, 13423779037, 232729381165100, 146367546237420097, 8864305651125125485354, 100000100010100010100010101101, 193529735150413879906083607547512
Offset: 1

Views

Author

Jonathan Vos Post, Sep 28 2006

Keywords

Comments

Main diagonal of the infinite array T(k,n) = 1 + Sum_{i=1..k} n^prime(i).
a(n) is prime for n = 1, 2, 4 -- what is the next prime in the sequence?
The next prime in the sequence is for n = 20. It has 93 digits. - Harvey P. Dale, Jan 18 2017

Examples

			a(1) = 2 = 1 + 1^2.
a(2) = 13 = 1 +2^2 +2^3.
a(3) = 280 = 1 +3^2 +3^3 +3^5.
a(4) = 17489 = 1 +4^2 +4^3 +4^5 +4^7.
a(5) = 48909526 = 1 +5^2 +5^3 +5^5 +5^7 +5^11.
a(6) = 13423779037 = 1 +6^2 +6^3 +6^5 +6^7 +6^11 +6^13.
a(7) = 232729381165100 = 1 +7^2 +7^3 +7^5 +7^7 +7^11 +7^13 +7^17.
a(8) = 146367546237420097 = 1 +8^2 +8^3 +8^5 +8^7 +8^11 +8^13 +8^17 +8^19.
		

Crossrefs

Programs

  • Magma
    [1 + (&+[n^NthPrime(j): j in [1..n]]): n in [1..15]]; // G. C. Greubel, Jul 21 2021
    
  • Mathematica
    Table[Total[n^Prime[Range[n]]]+1,{n,15}] (* Harvey P. Dale, Jan 18 2017 *)
  • Sage
    [1 + sum(n^nth_prime(j) for j in (1..n)) for n in (1..15)] # G. C. Greubel, Jul 21 2021

Formula

a(n) = 1 + n^2 + n^3 + n^5 + ... + n^prime(n).

A135484 a(n) = Sum_{i=1..n} i^prime(i), where prime(i) denotes i-th prime number.

Original entry on oeis.org

1, 9, 252, 16636, 48844761, 13109538777, 232643623525984, 144347831699381856, 8863082467484200477785, 100000008863082467484200477785, 192043424966613562971631041769596
Offset: 1

Views

Author

Ctibor O. Zizka, Feb 07 2008

Keywords

Crossrefs

Partial sums of A062481.

Programs

  • Mathematica
    f[n_] := Sum[i^Prime@i, {i, n}]; Array[f, 12] (* Robert G. Wilson v, Feb 12 2008 *)
    Accumulate[Table[n^Prime[n],{n,15}]] (* Harvey P. Dale, Nov 30 2023 *)
  • PARI
    a(n) = sum(k=1, n, k^prime(k)); \\ Michel Marcus, Oct 15 2016

Extensions

Edited and extended by Robert G. Wilson v, Feb 12 2008

A318199 a(n) is the largest integer m such that m^n <= n^prime(n).

Original entry on oeis.org

1, 2, 6, 11, 34, 48, 112, 139, 274, 794, 860, 2125, 3259, 3313, 4842, 9741, 18637, 17946, 32306, 41558, 39471, 66148, 82046, 131305, 265464, 313781, 288660, 339008, 313761, 366288, 1287573, 1451134, 2014343, 1824089, 3743848, 3371509, 4510880, 5976406
Offset: 1

Views

Author

Stefano Spezia, Aug 21 2018

Keywords

Comments

The sequence is not monotonic, for example a(18) < a(17).
Conjecture: there is no run of consecutive increasing terms with more than 17 terms.

Crossrefs

Programs

  • Maple
    Digits:= 2000:
    a:= n-> floor(n^(ithprime(n)/n)):
    seq(a(n),n=1..40); # Muniru A Asiru, Sep 17 2018
  • Mathematica
    a[n_]:=Floor[n^(Prime[n]/n)]; Array[a,40]
  • PARI
    a(n) = sqrtnint(n^prime(n), n); \\ Michel Marcus, Mar 12 2020
    vector(40, n, a(n))

Formula

a(n) = floor(n^(prime(n)/n)).
a(n) = floor(A062481(n)^(1/n)).

A076955 Product_{i=1..n} i^prime(i).

Original entry on oeis.org

1, 8, 1944, 31850496, 1555200000000000, 20311991333683200000000000, 4725188984058417024032990822400000000000, 680971499131541103151460312870118086801149132800000000000
Offset: 1

Views

Author

Amarnath Murthy, Oct 20 2002

Keywords

Crossrefs

n-th partial product of A062481.
Cf. A076954.

Programs

  • Maple
    seq(product(i^ithprime(i),i=1..n),n=1..13);

Formula

a(1) =1, a(n+1) = a(n)*(n+1)^prime(n+1).

Extensions

More terms from Sascha Kurz, Jan 22 2003

A096250 Decimal expansion of Sum_{n>=1} 1/n^prime(n).

Original entry on oeis.org

1, 1, 2, 9, 1, 7, 6, 2, 8, 2, 0, 5, 0, 2, 6, 8, 4, 7, 4, 9, 3, 8, 2, 9, 8, 5, 6, 6, 7, 0, 3, 9, 0, 5, 3, 6, 8, 1, 4, 2, 5, 0, 0, 5, 4, 0, 3, 7, 4, 3, 9, 4, 6, 4, 9, 1, 0, 7, 2, 7, 6, 3, 2, 2, 4, 4, 3, 5, 8, 4, 7, 3, 3, 0, 7, 3, 9, 2, 8, 5, 4, 3, 4, 0, 7, 1, 0, 3, 2, 7, 9, 4, 3, 4, 1, 2, 7, 2, 8, 9, 3, 1, 6, 2, 9
Offset: 1

Views

Author

Cino Hilliard, Jul 31 2004

Keywords

Crossrefs

Cf. A062481 (n^prime(n)).

Programs

  • PARI
    xtothepx(n) = { local(x,s,a); default(realprecision,200); s=0; print1(1","); for(x=1,n,s+=1./x^prime(x)); a=Vec(Str(s)); for(x=3,n,print1(eval(a[x]),",")); print(); print(s) }
    
  • PARI
    suminf(n=1, 1/n^prime(n)) \\ Michel Marcus, Nov 18 2020

A160501 (n+1)^prime(n+1) + n^prime(n).

Original entry on oeis.org

9, 251, 16627, 48844509, 13109522141, 232643574681223, 144347818589843079, 8863082234840576951801, 100000008862938119652501095929, 192043424957750480504146841291811
Offset: 1

Views

Author

Cino Hilliard, May 15 2009

Keywords

Comments

a(2)=251 is the only prime found for n up to 10000 using The C/Gmp program in the link which is 17 times faster than the PARI routine.
Here there are divisibility rules: If prime(n) and prime(n+1) do not differ by 6, then n^2+n+1 is a divisor. So finding primes in this case will be difficult since 5/6 of the numbers are composite at the onset.
If another prime exists, it is larger than 418977 digits.

Examples

			For n = 3, 4^7 + 3^5 = 16627, the 3rd entry in the sequence.
		

Crossrefs

Cf. A160491.

Programs

  • Mathematica
    Table[n^Prime[n]+(n+1)^Prime[n+1],{n,10}] (* Harvey P. Dale, Sep 10 2016 *)
    Total/@Partition[Table[n^Prime[n] ,{n,15}],2,1] (* Harvey P. Dale, Sep 22 2020 *)
  • PARI
    ppower(n) = { for(x=1,n, y=(x+1)^prime(x+1) + x^prime(x); print1(y", ") ); }

Formula

a(n) = (n+1)^prime(n+1) + n^prime(n) = A062481(n)+A062481(n+1).

Extensions

Edited by R. J. Mathar, May 30 2009

A098137 a(n) = n^n + n^prime(n).

Original entry on oeis.org

2, 12, 270, 16640, 48831250, 13060740672, 232630514810750, 144115188092633088, 8862938119652888516418, 100000000000000000010000000000, 191943424957750480504432152962422, 8505622499821102144576131693030930382848, 4695452425098908797088971409337724910182721066
Offset: 1

Views

Author

Parthasarathy Nambi, Sep 27 2004

Keywords

Examples

			a(1) = 1^1 + 1^2 = 2.
a(2) = 2^2 + 2^3 = 12.
a(3) = 3^3 + 3^5 = 270.
		

Crossrefs

Programs

Formula

a(n) = A000312(n) + A062481(n). - Michel Marcus, Aug 27 2015

Extensions

More terms from Stefan Steinerberger, Feb 28 2006
a(12)-a(13) from Vincenzo Librandi, Aug 27 2015

A215633 Decimal expansion of Sum_{n>=1} 1/n^(n^prime(n)).

Original entry on oeis.org

1, 0, 0, 3, 9, 0, 6, 2, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1
Offset: 1

Views

Author

Balarka Sen, Aug 18 2012

Keywords

Comments

Is this a finite sequence? (or equivalently, is this constant rational?)
Unlikely: the "apparent" rationality seems to be caused by the rapid growth of the denominators; one may instead speculate that the value is transcendental. - Joerg Arndt, Feb 05 2013
The constant is approximately 257/256 (see A021260).

Examples

			1.00390625000000000000000000... = 1 + 1/2^8 + 1/3^243 + 1/4^16384+...
		

Crossrefs

Cf. A062481.

Programs

  • PARI
    suminf(n=1,1/n^(n^prime(n)))

A259654 a(n) = prime(n)^prime(n) - prime(n)^n.

Original entry on oeis.org

2, 18, 3000, 821142, 285311509560, 302875101765444, 827240261885926425504, 1978419655660296605560938, 20880467999847912032553880249104, 2567686153161211134561828214310308893183268, 17069174130723235958610643029033906279148329600
Offset: 1

Views

Author

Ilya Gutkovskiy, Jul 02 2015

Keywords

Crossrefs

Programs

  • Magma
    [NthPrime(n)^NthPrime(n)-NthPrime(n)^n: n in [1..12]]; // Vincenzo Librandi, Jul 03 2015
    
  • Mathematica
    Table[Prime[n]^Prime[n] - Prime[n]^n, {n, 1, 10}]
    #[[1]]^#[[1]]-#[[1]]^#[[2]]&/@Table[{Prime[n],n},{n,15}] (* Harvey P. Dale, Nov 10 2016 *)
  • PARI
    a(n,p=prime(n))=p^p - p^n \\ Charles R Greathouse IV, Jul 22 2016

Formula

a(n) = A051674(n) - A062457(n).
Showing 1-10 of 10 results.