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.

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A102615 Nonprime numbers of order 2.

Original entry on oeis.org

1, 8, 10, 14, 15, 16, 20, 22, 24, 25, 27, 30, 32, 33, 35, 36, 38, 39, 40, 44, 46, 48, 49, 50, 51, 54, 55, 56, 58, 62, 63, 64, 66, 68, 69, 70, 72, 75, 76, 77, 78, 80, 82, 85, 86, 87, 88, 90, 92, 93, 94, 96, 99, 100, 102, 104, 105, 108, 110, 111, 114, 115, 116, 117, 118, 120
Offset: 1

Views

Author

Cino Hilliard, Jan 31 2005

Keywords

Comments

nps(n,0) -> list nonprime(n) or the sequence of nonprime numbers. nps(n,1) -> list nonprime(nonprime(n)) or nps of order 1 nps(n,2) -> list nonprime(nonprime(nonprime(n))) or nps of order 2 ..... The order is the number of nestings - 1. We avoid the nestings in the script with a loop.
Nonprimes (A018252) with nonprime (A018252) subscripts. a(n) U A078782(n) = A018252(n), a(n+1) U A175250(n) = A018252(n) for n >= 1. a(n) = nonprime(nonprime(n)) = A018252(A018252(n)). a(4) = 14 because a(4) = b(b(4)) = b(8) = 14, b = nonprime. a(1) = 1, a(n) = nonprimes (A018252) with composite (A002808) subscripts for n >=2. [Jaroslav Krizek, Mar 13 2010]

Examples

			Nonprime(2) = 4.
Nonprime(4) = 8 the second entry.
		

Crossrefs

Cf. A018252.
Let A = primes A000040, B = nonprimes A018252. The 2-level compounds are AA = A006450, AB = A007821, BA = A078782, BB = A102615. The 3-level compounds AAA, AAB, ..., BBB are A038580, A049078, A270792, A102617, A270794, A270796, A102216.

Programs

  • Maple
    # For Maple code for the prime/nonprime compound sequences (listed in cross-references) see A003622.  - N. J. A. Sloane, Mar 30 2016
  • Mathematica
    nonPrime[n_] := FixedPoint[n + PrimePi[ # ] &, n]; Nest[nonPrime, Range[66], 2] (* Robert G. Wilson v, Feb 04 2005 *)
  • PARI
    \We perform nesting(s) with a loop. cics(n,m) = { local(x,y,z); for(x=1,n, z=x; for(y=1,m+1, z=composite(z); ); print1(z",") ) } composite(n) = \ The n-th composite number. 1 is defined as a composite number. { local(c,x); c=1; x=0; while(c <= n, x++; if(!isprime(x),c++); ); return(x) }

Extensions

Edited by Robert G. Wilson v, Feb 04 2005

A078782 Nonprimes (A018252) with prime (A000040) subscripts.

Original entry on oeis.org

4, 6, 9, 12, 18, 21, 26, 28, 34, 42, 45, 52, 57, 60, 65, 74, 81, 84, 91, 95, 98, 106, 112, 119, 128, 133, 135, 141, 143, 147, 165, 170, 177, 180, 192, 195, 203, 209, 214, 220, 228, 231, 244, 246, 250, 253, 267, 284, 288, 290, 295, 301, 303, 316, 323, 329, 336
Offset: 1

Views

Author

Joseph L. Pe, Jan 09 2003

Keywords

Comments

a(n) = A018252(A000040(n)). Subsequence of A175250 (nonprimes (A018252) with noncomposite (A008578) subscripts), a(n) = A175250(n+1). a(n) U A102615(n) = A018252(n). [From Jaroslav Krizek, Mar 13 2010]

Examples

			a(4) = nonprime(prime(4)) = nonprime(7) = 12.
		

Crossrefs

Let A = primes A000040, B = nonprimes A018252. The 2-level compounds are AA = A006450, AB = A007821, BA = A078782, BB = A102615. The 3-level compounds AAA, AAB, ..., BBB are A038580, A049078, A270792, A102617, A270794, A270796, A102216.

Programs

  • Python
    from sympy import prime, composite
    def A078782(n): return composite(prime(n)-1) # Chai Wah Wu, Nov 13 2024

Extensions

Corrected by Jaroslav Krizek, Mar 13 2010

A057847 Primes p whose order of primeness A078442(p) is at least 10.

Original entry on oeis.org

648391, 9737333, 174440041, 718064159, 3657500101, 7069067389, 16123689073, 22742734291, 36294260117, 64988430769, 88362852307, 136395369829, 175650481151, 200147986693, 243504973489, 318083817907, 414507281407
Offset: 1

Views

Author

Robert G. Wilson v, Nov 10 2000

Keywords

Crossrefs

Programs

Formula

a(n) = prime(A057851(n)). - Andrew Howroyd, Nov 17 2024

Extensions

Name clarified by Andrew Howroyd, Nov 17 2024

A057849 Primes p whose order of primeness A078442(p) is at least 7.

Original entry on oeis.org

709, 5381, 52711, 167449, 648391, 1128889, 2269733, 3042161, 4535189, 7474967, 9737333, 14161729, 17624813, 19734581, 23391799, 29499439, 37139213, 38790341, 50728129, 56011909, 59053067, 68425619, 77557187, 87019979, 101146501, 113256643, 119535373, 127065427
Offset: 1

Views

Author

Robert G. Wilson v, Nov 10 2000

Keywords

Crossrefs

Programs

  • Maple
    a:= ithprime@@7;
    seq(a(n), n=1..30);  # Alois P. Heinz, Jun 14 2015
  • Mathematica
    Nest[ Prime, Range[35], 7] (* Robert G. Wilson v, Mar 15 2004 *)
  • PARI
    list(lim)=my(v=List(), q, r, s, t, u, vv); forprime(p=2, lim, if(isprime(q++) && isprime(r++) && isprime(s++) && isprime(t++) && isprime(u++) && isprime(vv++), listput(v, p))); Vec(v) \\ Charles R Greathouse IV, Feb 16 2017

Extensions

Name clarified by Andrew Howroyd, Nov 17 2024

A057850 Primes p whose order of primeness A078442(p) is at least 8.

Original entry on oeis.org

5381, 52711, 648391, 2269733, 9737333, 17624813, 37139213, 50728129, 77557187, 131807699, 174440041, 259336153, 326851121, 368345293, 440817757, 563167303, 718064159, 751783477, 997525853, 1107276647, 1170710369, 1367161723
Offset: 1

Views

Author

Robert G. Wilson v, Nov 10 2000

Keywords

Comments

Union of A058325-A058328, A093046 etc. - R. J. Mathar, Jul 07 2012

Crossrefs

Programs

  • Mathematica
    Nest[ Prime, Range[35], 8] (* Robert G. Wilson v, Mar 15 2004 *)
  • PARI
    list(lim)=my(v=List(), q, r, s, t, u, vv, w); forprime(p=2, lim, if(isprime(q++) && isprime(r++) && isprime(s++) && isprime(t++) && isprime(u++) && isprime(vv++) && isprime(w++), listput(v, p))); Vec(v) \\ Charles R Greathouse IV, Feb 19 2017

Formula

a(n) = A049090(A049090(n)). - James G. Merickel, Feb 14 2010
a(n) = A000040(A057849(n)). - R. J. Mathar, Jul 07 2012

Extensions

Name clarified by Andrew Howroyd, Nov 17 2024

A057851 Primes p whose order of primeness A078442(p) is at least 9.

Original entry on oeis.org

52711, 648391, 9737333, 37139213, 174440041, 326851121, 718064159, 997525853, 1559861749, 2724711961, 3657500101, 5545806481, 7069067389, 8012791231, 9672485827, 12501968177, 16123689073, 16917026909, 22742734291
Offset: 1

Views

Author

Robert G. Wilson v, Nov 10 2000

Keywords

Crossrefs

Programs

  • Mathematica
    Nest[ Prime, Range[35], 9] (* Robert G. Wilson v, Mar 15 2004 *)
  • PARI
    list(lim)=my(v=List(), q, r, s, t, u, vv, w, x); forprime(p=2, lim, if(isprime(q++) && isprime(r++) && isprime(s++) && isprime(t++) && isprime(u++) && isprime(vv++) && isprime(w++) && isprime(x++), listput(v, p))); Vec(v) \\ Charles R Greathouse IV, Feb 19 2017

Extensions

Name clarified by Andrew Howroyd, Nov 17 2024

A058332 Primes p whose order of primeness A078442(p) is at least 11.

Original entry on oeis.org

9737333, 174440041, 3657500101, 16123689073, 88362852307, 175650481151, 414507281407, 592821132889, 963726515729, 1765037224331, 2428095424619, 3809491708961, 4952019383323, 5669795882633, 6947574946087, 9163611272327
Offset: 1

Views

Author

Robert G. Wilson v, Dec 12 2000

Keywords

Crossrefs

Programs

Formula

a(n) = prime(A057847(n)). - Andrew Howroyd, Nov 17 2024

Extensions

Name clarified by Andrew Howroyd, Nov 17 2024

A093047 Primes p whose order of primeness A078442(p) is at least 12.

Original entry on oeis.org

174440041, 3657500101, 88362852307, 414507281407, 2428095424619, 4952019383323, 12055296811267, 17461204521323, 28871271685163, 53982894593057, 75063692618249, 119543903707171, 156740126985437, 180252380737439, 222334565193649
Offset: 1

Views

Author

Robert G. Wilson v, Mar 15 2000

Keywords

Comments

Primes p whose primeness is > 12: 3657500101, 88362852307, 2428095424619, 12055296811267, 75063692618249, 156740126985437, ..., . - Robert G. Wilson v, Mar 15 2000

Crossrefs

Programs

Formula

a(n) = A058332(prime(n)). - Andrew Howroyd, Nov 17 2024

Extensions

Name clarified by Andrew Howroyd, Nov 17 2024

A102617 Primes p(n) such that n is a second-order nonprime number.

Original entry on oeis.org

2, 19, 29, 43, 47, 53, 71, 79, 89, 97, 103, 113, 131, 137, 149, 151, 163, 167, 173, 193, 199, 223, 227, 229, 233, 251, 257, 263, 271, 293, 307, 311, 317, 337, 347, 349, 359, 379, 383, 389, 397, 409, 421, 439, 443, 449, 457, 463, 479, 487, 491, 503, 523, 541
Offset: 1

Views

Author

Cino Hilliard, Jan 31 2005

Keywords

Comments

The prime/nonprime compound sequence ABB. - N. J. A. Sloane, Apr 06 2016

Examples

			Nonprime(4) = 8.
The 8th prime is 19, the second entry.
		

Crossrefs

Let A = primes A000040, B = nonprimes A018252. The 2-level compounds are AA = A006450, AB = A007821, BA = A078782, BB = A102615. The 3-level compounds AAA, AAB, ..., BBB are A038580, A049078, A270792, A102617, A270794, A270796, A102216.

Programs

  • Maple
    For Maple code for the prime/nonprime compound sequences (listed in cross-references) see A003622. - N. J. A. Sloane, Mar 30 2016
  • Mathematica
    nonPrime[n_Integer] := FixedPoint[n + PrimePi[ # ] &, n]; Prime /@ nonPrime /@ nonPrime /@ Range[54] (* Robert G. Wilson v, Feb 04 2005 *)
  • PARI
    \We perform nesting(s) with a loop. cips(n,m) = { local(x,y,z); for(x=1,n, z=x; for(y=1,m+1, z=composite(z); ); print1(prime(z)",") ) } composite(n) = \ The n-th composite number. 1 is defined as a composite number. { local(c,x); c=1; x=0; while(c <= n, x++; if(!isprime(x),c++); ); return(x) }

Extensions

Edited by Robert G. Wilson v, Feb 04 2005

A270792 The prime/nonprime compound sequence ABA.

Original entry on oeis.org

7, 13, 23, 37, 61, 73, 101, 107, 139, 181, 197, 239, 269, 281, 313, 373, 419, 433, 467, 499, 521, 577, 613, 653, 719, 751, 761, 811, 823, 853, 977, 1013, 1051, 1069, 1163, 1187, 1237, 1289, 1307, 1373, 1439, 1453, 1549, 1559, 1583
Offset: 1

Views

Author

N. J. A. Sloane, Mar 30 2016

Keywords

Crossrefs

Let A = primes A000040, B = nonprimes A018252. The 2-level compounds are AA = A006450, AB = A007821, BA = A078782, BB = A102615. The 3-level compounds AAA, AAB, ..., BBB are A038580, A049078, A270792, A102617, A270794, A270796, A102216.

Programs

  • Maple
    # For Maple code for the prime/nonprime compound sequences (listed in cross-references) see A003622.  - N. J. A. Sloane, Mar 30 2016
Previous Showing 11-20 of 43 results. Next