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 1-4 of 4 results.

A134246 Quotients A134245(n)/A134244(n).

Original entry on oeis.org

2, 4, 22, 64, 132, 231, 5472, 8877, 34635, 57550, 75542, 636667, 739799, 1291879, 2081880, 3064827, 4039368, 9433189, 16966370, 211947608, 367298045, 1101086463, 1541079585, 16915330550, 20775909209, 24450416187, 575276374739, 707965641746, 3731987263894
Offset: 1

Views

Author

Enoch Haga, Oct 15 2007, Oct 16 2007

Keywords

Comments

Alternatively: integers of the form A007468(j)/j sorted w.r.t. increasing j. - R. J. Mathar, Nov 16 2007

Crossrefs

Cf. A134244 A134245.

Programs

Extensions

Better definition from R. J. Mathar, Nov 16 2007
a(24)-a(26) from Max Alekseyev, Jul 29 2011
a(27)-a(28) from Chai Wah Wu, Jan 14 2020
a(29) from Chai Wah Wu, Jan 16 2020

A134244 Indices k such that k divides A007468(k).

Original entry on oeis.org

1, 2, 4, 6, 8, 10, 38, 47, 86, 108, 122, 322, 345, 446, 556, 665, 756, 1122, 1476, 4838, 6274, 10556, 12383, 38774, 42776, 46239, 210215, 232276, 517144, 1125321, 2561652
Offset: 1

Views

Author

Enoch Haga, Oct 15 2007, Oct 16 2007

Keywords

Crossrefs

Cf. A134245, A134246.

Programs

  • PARI
    { p=2 ; i=1 ; for(j=1,13000, psum=p ; for(k=2,j, p=nextprime(p+1) ; psum += p ; ) ; if(psum % j ==0, print(j) ; ) ; p=nextprime(p+1) ; ) ; } \\ R. J. Mathar, Jan 24 2008

Extensions

Better definition from R. J. Mathar, Nov 16 2007
Entries checked by R. J. Mathar, Jan 24 2008
a(24)-a(26) from Max Alekseyev, Jul 29 2011
a(27)-a(28) from Chai Wah Wu, Jan 14 2020
a(29) from Chai Wah Wu, Jan 16 2020
a(30)-a(31) from Giovanni Resta, Jan 24 2020

A134179 Primes in A007468.

Original entry on oeis.org

2, 31, 199, 659, 1601, 5693, 38917, 51797, 84463, 697373, 8059169, 8510617, 9465251, 28268543, 36254039, 40121999, 48667219, 54973229, 63627491, 90443813, 97626083, 102534899, 110364689, 139100699, 161967391, 183528421, 219566989
Offset: 1

Views

Author

Enoch Haga, Oct 16 2007

Keywords

Links

Crossrefs

Cf. A134180, A134244, A134245, A134246.

Programs

  • Mathematica
    n = 1000; Select[Total /@ TakeList[Prime[Range@(n(n+1)/2)], Range@n], PrimeQ] (* Zhining Yang, May 22 2023 *)
  • UBASIC
    10 K=1
20 A=nxtprm(A):B=B+A:C=C+1: if C<>K then 20:else 30
30 L=B/K
31 print K;B;:Q=prmdiv(B): if Q=B then print B;"-":stop:else 40
40 B=0:K=K+1:C=0:goto 20

Extensions

Edited by Zak Seidov, Feb 05 2010

A134180 Indices of primes in A007468.

Original entry on oeis.org

1, 3, 5, 7, 9, 13, 23, 25, 29, 55, 117, 119, 123, 173, 187, 193, 205, 213, 223, 249, 255, 259, 265, 285, 299, 311, 329, 351, 393, 397, 411, 483, 487, 513, 515, 525, 563, 587, 597, 607, 637, 645, 647, 679, 709, 789, 871, 877, 911, 953, 971, 985, 1015, 1051, 1075
Offset: 1

Views

Author

Enoch Haga, Oct 16 2007

Keywords

Comments

Compute sums of k distinct sequential primes (no overlap). If the sums are prime add their indices to the sequence.

Examples

			a(2)=3 because this k value is the index for the next 3 primes in sequence to be summed. k=1 is 2, k=2 is 3+5 and k=3 is 7+11+13=31. The sums at k=1 and k=3 are prime, while k=2 is composite.

Links

Crossrefs

Cf. A007468. Corresponding primes are listed in A134179.
Cf. A134244, A134245, A134246.

Programs

  • UBASIC
    10 K=1
  20 A=nxtprm(A): B=B+A: C=C+1: if C<>K then 20: else 30
  30 L=B/K
  31 print K;B;: Q=prmdiv(B): if Q=B then print B; "-": stop: else 40
  40 B=0: K=K+1: C=0: goto 20
Showing 1-4 of 4 results.

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