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 14 results. Next

A168219 Naturals n for which 1 + 10*n^3 (A168147) is prime.

Original entry on oeis.org

1, 3, 4, 6, 15, 16, 18, 24, 27, 30, 31, 36, 37, 43, 51, 52, 57, 60, 73, 75, 81, 82, 87, 90, 93, 106, 108, 109, 114, 145, 154, 159, 160, 163, 165, 171, 174, 175, 178, 196, 201, 204, 207, 208, 211, 220, 222, 225, 228, 234
Offset: 1

Views

Author

Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Nov 20 2009

Keywords

Comments

It is conjectured that sequence is infinite.
No three consecutive integers n are in the list. [Proof: An integer of the form n=3*k+2 generates 1+10*n^3 = 9*(9+30*k^3+60*k^2+40*k) which is divisible through 9, hence not a prime, so these n are not in the list. Since every third integer is of this form == 2 (mod 3), no more than two consecutive integers can be in the sequence.] [Zak Seidov, Nov 24 2009]

Examples

			(1) 1+10*1^3=11 gives a(1)=1
(2) 1+10*3^3=271=3^4 gives a(2)=3
(3) 1+10*37^3=506531 gives a(13)=37
		

References

  • Harold Davenport, Multiplicative Number Theory, Springer-Verlag New-York 1980.
  • Leonard E. Dickson: History of the Theory of numbers, vol. I, Dover Publications 2005.
  • Paulo Ribenboim, The New Book of Prime Number Records, Springer 1996.

Crossrefs

Programs

  • Mathematica
    Select[Range[100], PrimeQ[1 + 10*#^3] &] (* G. C. Greubel, Jul 16 2016 *)
  • PARI
    for(n=1,2e2, isprime(n^3*10+1) && print1(n", "))  \\ M. F. Hasler, Jul 24 2011

A168327 Primes of concatenated form "1 n^3".

Original entry on oeis.org

11, 127, 12197, 135937, 159319, 11092727, 11295029, 11860867, 12685619, 14330747, 14826809, 15000211, 15929741, 16128487, 18869743, 19393931, 124137569, 126198073, 127818127, 129503629, 138958219, 150243409, 154439939, 160698457, 175686967, 191733851, 195443993
Offset: 1

Views

Author

Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Nov 23 2009

Keywords

Comments

(1) It is conjectured that sequence is infinite.
(2) These are primes all with "leading" digit "1", they are concatenations of two cubic numbers: 1^3 and n^3, n is a natural.

Examples

			(1) 10^1+1^3=11 = prime(5) = a(1).
(2) 10^2+3^3=127 = prime(31) = a(2).
(3) 10^4+13^3=12197 = prime(1458) = a(3).
		

References

  • Harold Davenport, Multiplicative Number Theory, Springer-Verlag New-York 1980
  • Leonard E. Dickson: History of the Theory of numbers, vol. I, Dover Publications 2005
  • Paulo Ribenboim, The New Book of Prime Number Records, Springer 1996

Crossrefs

Programs

  • Mathematica
    Select[FromDigits[Join[{1},IntegerDigits[#]]]&/@(Range[500]^3),PrimeQ] (* Harvey P. Dale, May 16 2012 *)

Formula

If n^3 is a d-digit number and d no multiple of 3, then p=10^d+n^3, where n is odd and no multiple of 5.
a(n) = c+10^A055642(c) where c=A167725(n). - R. J. Mathar, Nov 23 2009

Extensions

Edited by Charles R Greathouse IV, Apr 24 2010

A173836 Natural numbers n such that the concatenation 1331//n^3 is a prime number.

Original entry on oeis.org

21, 27, 29, 41, 101, 119, 141, 171, 173, 177, 191, 197, 219, 243, 267, 291, 309, 327, 333, 369, 371, 383, 411, 417, 1019, 1049, 1059, 1091, 1157, 1163, 1211, 1311, 1337, 1343, 1359, 1371, 1379, 1409, 1461, 1473, 1481, 1503, 1521, 1593, 1599, 1613, 1637
Offset: 1

Views

Author

Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Feb 26 2010

Keywords

Comments

Given the cube n^3 with k = A111393(n) decimal digits, we have to check whether the concatenation, 11^3 * 10^k + n^3, is a prime.
The number k of digits that 1331=11^3 is shifted is not a multiple of 3,
because the form a^3+b^3 = (a^2+a*b+b^2) * (a - b) cannot construct a prime.

Examples

			21 is in the sequence because 21^3=9261, and the concatenation is 13319261=prime(868687).
27 is in the sequence because 27^3=19683, and the concatenation is 133119683=prime(7545064).
		

References

  • K. Haase, P. Mauksch: Spass mit Mathe, Urania-Verlag Leipzig, Verlag Dausien Hanau, 2. Auflage 1985

Crossrefs

Programs

  • Mathematica
    Select[Range[2000],PrimeQ[FromDigits[Join[{1,3,3,1}, IntegerDigits[ #^3]]]]&] (* Harvey P. Dale, Oct 14 2011 *)

Extensions

Comments sligthly rephrased - R. J. Mathar, Mar 05 2010

A168417 Primes q for which 1 concatenated with q^3 (A168327) is prime.

Original entry on oeis.org

3, 13, 103, 109, 139, 163, 181, 211, 379, 457, 463, 1021, 1087, 1123, 1201, 1249, 1303, 1381, 1579, 1597, 1609, 1699, 1861, 1873, 1987, 2011, 2029, 2053, 2143, 2221, 2281, 2341, 2473, 2503, 2557, 2731, 2857, 3061, 3067, 3217, 3253, 3271, 3319, 3331, 3517
Offset: 1

Views

Author

Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Nov 25 2009

Keywords

Comments

It is conjectured that this sequence is infinite.

Examples

			(1) "1 3^3"=10^2+3^3=127=prime(31) gives a(1)=3=prime(2)
(2) "1 103^3"=10^7+103^3=11092727=prime(732258) gives a(3)=103=prime(27)
		

References

  • Harold Davenport, Multiplicative Number Theory, Springer-Verlag New-York 1980
  • Leonard E. Dickson: History of the Theory of numbers, vol. I, Dover Publications 2005

Crossrefs

A168147 Primes of the form p = 1 + 10*n^3 for a natural number n
A168327 Primes of concatenated form p= "1 n^3"
A168375 Natural numbers n for which the concatenation p= "1 n^3" is prime

Programs

  • Mathematica
    Select[Prime[Range[500]],PrimeQ[FromDigits[Join[{1},IntegerDigits[ #^3]]]]&] (* Harvey P. Dale, Jan 21 2013 *)

Extensions

Edited and extended by Charles R Greathouse IV, Apr 23 2010

A173579 Natural numbers n which give primes when 1331 = 11^3 is prefixed.

Original entry on oeis.org

3, 17, 21, 53, 57, 69, 83, 87, 107, 119, 123, 153, 207, 227, 243, 249, 251, 261, 269, 279, 293, 299, 327, 329, 333, 339, 347, 377, 381, 383, 399, 411, 431, 437, 443, 471, 489, 497, 513, 521, 527, 549, 567, 573, 579, 587, 591, 597, 599, 611, 633, 641, 647, 657
Offset: 1

Views

Author

Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Feb 22 2010

Keywords

Comments

Concatenation of N = 1331 = 11^3 = palindrome(113) and natural n is a prime. No zeros "between" N and n.
13 = emirp(1) = prime(6), R(13) = 31 = emirp(3) = prime(11).
Necessarily n = 3 * k or n = 3 * k + 2, but not n = 3 * k + 1, because sod(1331) = 8. So no prime twins are terms of the sequence.

Examples

			13313 = prime(1581) => a(1) = 3.
133117 = prime(12425) => a(2) = 17.
133103, 133109 are prime, but "0" included: "03" resp. "09" are no terms of the sequence.
		

References

  • Leonard E. Dickson: History of the Theory of numbers, vol. I, Dover Publications 2005
  • K. Haase, P. Mauksch: Spass mit Mathe, Urania-Verlag Leipzig, Verlag Dausien Hanau, 2. Auflage 1985
  • Theo Kempermann: Zahlentheoretische Kostproben, Harri Deutsch, 2. aktualisierte Auflage 2005

Crossrefs

Programs

  • Mathematica
    Select[Range[700],PrimeQ[1331*10^IntegerLength[#]+#]&] (* Harvey P. Dale, Jun 25 2020 *)
  • PARI
    isok(n) = isprime(n + 1331*10^(length(Str(n)))); \\ Michel Marcus, Aug 27 2013

A168274 Primes p such that 10*p^3 + 1 is prime.

Original entry on oeis.org

3, 31, 37, 43, 73, 109, 163, 211, 241, 313, 337, 409, 499, 673, 739, 757, 907, 1033, 1039, 1069, 1237, 1327, 1447, 1483, 1489, 1597, 1663, 1741, 1777, 1933, 2083, 2143, 2251, 2437, 2683, 2797, 3001, 3181, 3307, 3319, 3463, 3739, 3793, 4051
Offset: 1

Views

Author

Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Nov 22 2009

Keywords

Comments

Subsequence of A168219.

Examples

			10*3^3+1 = 271 is prime, so prime 3 is in the sequence.
10*313^3+1 = 306642971 is prime, so prime 313 is in the sequence.
		

Crossrefs

Programs

  • Magma
    [ p: p in PrimesUpTo(5000) | IsPrime(10*p^3+1) ]; // Vincenzo Librandi, Jan 29 2011
    
  • Mathematica
    Select[Prime[Range[100]], PrimeQ[10*#^3 + 1] &] (* G. C. Greubel, Jul 16 2016 *)
  • PARI
    select(p->isprime(10*p^3+1), primes(1000)) \\ Charles R Greathouse IV, Jul 16 2016

Extensions

Edited by Charles R Greathouse IV, Apr 24 2010

A168375 Natural numbers n for which the concatenation p= "1 n^3" (A168327) is prime.

Original entry on oeis.org

1, 3, 13, 33, 39, 103, 109, 123, 139, 163, 169, 171, 181, 183, 207, 211, 289, 297, 303, 309, 339, 369, 379, 393, 423, 451, 457, 463, 1021, 1027, 1047, 1053, 1057, 1081, 1087, 1111, 1123, 1161, 1189, 1201, 1249, 1273, 1293, 1303, 1329, 1339, 1351, 1381, 1387
Offset: 1

Views

Author

Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Nov 24 2009

Keywords

Comments

It is conjectured that sequence is infinite

Examples

			(1) "1 1^3"=10^1+1^3=11=prime(5) gives a(1)=1
(2) "1 3^3"=10^2+3^3=127=prime(31) gives a(2)=3
(3) "1 13^3"=10^4+13^3=12197=prime(1458) gives a(3)=13
		

References

  • Harold Davenport, Multiplicative Number Theory, Springer-Verlag New-York 1980
  • Friedhelm Padberg, Elementare Zahlentheorie, Spektrum Akademischer Verlag, 2. Auflage 1991
  • Paulo Ribenboim, The New Book of Prime Number Records, Springer 1996

Crossrefs

Cf. A000040 The prime numbers
Cf. A168147 Primes of the form p = 1 + 10*n^3 for a natural number n
Cf. A168327 Primes of concatenated form p= "1 n^3"
Cf. A167535 Concatenation of two square numbers which give a prime

Formula

If n^3 is a d-digit natural number, odd and no multiple of 5, and d no multiple of 3, then p=10^d+n^3

Extensions

Edited by Charles R Greathouse IV, Apr 23 2010

A173733 Primes p which give primes when 1331 = 11^3 is prefixed (see A173579).

Original entry on oeis.org

3, 17, 53, 83, 107, 227, 251, 269, 293, 347, 383, 431, 443, 521, 587, 599, 641, 647, 683, 719, 761, 773, 821, 857, 929, 1031, 1097, 1217, 1223, 1301, 1367, 1409, 1433, 1451, 1619, 1637, 1709, 1787, 1973, 2081, 2087, 2129, 2399, 2477, 2591, 2633, 2657, 2693
Offset: 1

Views

Author

Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Feb 23 2010

Keywords

Comments

N = 1331 = 11^3, p k-digit prime, to check if q = N * 10^k + p is prime
With exception of 3 necessarily p of form 3k+2, as sod(1331 = 8)

Examples

			13313 = prime(1581) => a(1) = prime(2) = 3
133117 = prime(12425) => a(2) = prime(7) = 17
133153 = prime(12427) => a(3) = prime(16) = 53
13311217 = prime(868166) => a(28) = prime(199) = 1217
13311223 = prime(868167) => a(29) = prime(200) = 1223
Note: two consecutive primes P = prime(n), Q = prime(n+1) yield consecutive prime concatenations "N P" = prime(m) and "N Q" = prime(m+1)
		

References

  • K. Haase, P. Mauksch: Spass mit Mathe, Urania-Verlag Leipzig, Verlag Dausien Hanau, 2. Auflage 1985
  • Helmut Kracke, Mathe-musische Knobelisken, Duemmler Bonn, 2. Auflage 1983

Crossrefs

Programs

  • Mathematica
    Select[Prime[Range[400]],PrimeQ[FromDigits[Join[{1,3,3,1}, IntegerDigits[ #]]]]&] (* Harvey P. Dale, Jun 09 2015 *)

Extensions

Edited and extended by Charles R Greathouse IV, Apr 24 2010

A176722 Primes of the form k^3 + 13, k >= 0.

Original entry on oeis.org

13, 229, 1013, 1741, 39317, 64013, 74101, 157477, 438989, 551381, 830597, 1906637, 2000389, 4096013, 7077901, 9261013, 10941061, 15625013, 16003021, 21024589, 24897101, 27000013, 69934541, 74088013, 79507013, 93576677, 122023949
Offset: 1

Views

Author

Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Apr 25 2010

Keywords

Comments

Necessarily, k = 6 * j or k = 6 * j + 4.
Values of k corresponding to terms of the sequence: 0, 6, 10, 12, 34, 40, 42, 54, 76, 82, 94, 124, 126, 160, 192, 210, 222, 250, 252, 276, 292, 300, 412, 420, 430, 454, 496, 502, 570, 586, 612, 622, 640, 670, 684, 712, 720, 724, 726, 756, 784, 822, 826, 874, 882, 894, 934, 952, 964, 1006, 1056.

Examples

			0^3 + 13 = 13 = prime(6) = a(1);
6^3 + 13 = 229 = prime(50) = a(2);
300^3 + 13 = 27000013 = prime(1683067) = a(22).
		

References

  • H. Rademacher, Topics in Analytic Number Theory, Springer-Verlag Berlin, 1973.

Crossrefs

Programs

  • Magma
    [a: n in [0..500]|IsPrime(a) where a is n^3+13] // Vincenzo Librandi, Dec 22 2010
  • Maple
    select(isprime,[seq(seq((6*j+m)^3+13,m=[0,4]),j=0..1000)]); # Robert Israel, Jun 28 2018
  • Mathematica
    Select[Range[0,1000]^3+13,PrimeQ]  (* Harvey P. Dale, Mar 12 2011 *)

A168487 Primes of the form 100n^3 + 27.

Original entry on oeis.org

127, 827, 6427, 12527, 34327, 219727, 491327, 1562527, 2438927, 3276827, 8518427, 16637527, 22698127, 43897627, 45653327, 51200027, 77868827, 119101627, 129502927, 140492827, 156089627, 177156127, 190662427, 251545627, 257135327
Offset: 1

Views

Author

Eva-Maria Zschorn (e-m.zschorn(AT)zaschendorf.km3.de), Nov 27 2009

Keywords

Comments

(1) These primes all with the end digits 2 and 7 are concatenations of two CUBIC numbers: "n^3 3^3".
(2) It is conjectured that sequence is infinite.

References

  • Harold Davenport, Multiplicative Number Theory, Springer-Verlag New-York 1980
  • Leonard E. Dickson: History of the Theory of numbers, vol. I, Dover Publications 2005
  • Friedhelm Padberg, Elementare Zahlentheorie, Spektrum Akademischer Verlag, 2. Auflage 1991

Crossrefs

A167535 Concatenation of two square numbers which give a prime
A168147 Primes of the form p = 1 + 10*n^3 for a natural number n
A168327 Primes of concatenated form p = "1 n^3"

Programs

  • Mathematica
    Select[100Range[140]^3+27,PrimeQ] (* Harvey P. Dale, Aug 22 2011 *)

Extensions

Edited by Charles R Greathouse IV, Apr 24 2010
Showing 1-10 of 14 results. Next