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 21 results. Next

A030430 Primes of the form 10*n+1.

Original entry on oeis.org

11, 31, 41, 61, 71, 101, 131, 151, 181, 191, 211, 241, 251, 271, 281, 311, 331, 401, 421, 431, 461, 491, 521, 541, 571, 601, 631, 641, 661, 691, 701, 751, 761, 811, 821, 881, 911, 941, 971, 991, 1021, 1031, 1051, 1061, 1091, 1151, 1171, 1181, 1201, 1231, 1291
Offset: 1

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Author

Keywords

Comments

Also primes of form 5*n+1 or equivalently 5*n+6.
Primes p such that the arithmetic mean of divisors of p^4 is an integer: A000203(p^4)/A000005(p^4) = C. - Ctibor O. Zizka, Sep 15 2008
Being a subset of A141158, this is also a subset of the primes of form x^2-5*y^2. - Tito Piezas III, Dec 28 2008
5 is quadratic residue of primes of this form. - Vincenzo Librandi, Jun 25 2014
Primes p such that 5 divides sigma(p^4), cf. A274397. - M. F. Hasler, Jul 10 2016

Crossrefs

Cf. A024912, A045453, A049511, A081759, A017281, A010051, A004615 (multiplicative closure).
Cf. A001583 (subsequence).
Union of A132230 and A132232. - Ray Chandler, Apr 07 2009

Programs

  • Haskell
    a030430 n = a030430_list !! (n-1)
    a030430_list = filter ((== 1) . a010051) a017281_list
    -- Reinhard Zumkeller, Apr 16 2012
    
  • Mathematica
    Select[Prime@Range[210], Mod[ #, 10] == 1 &] (* Ray Chandler, Dec 06 2006 *)
    Select[Range[11,1291,10],PrimeQ] (*Zak Seidov, Aug 14 2011*)
  • PARI
    is(n)=n%10==1 && isprime(n) \\ Charles R Greathouse IV, Sep 06 2012
    
  • PARI
    lista(nn) = forprime(p=11, nn, if(p%10==1, print1(p, ", "))) \\ Iain Fox, Dec 30 2017

Formula

a(n) = 10*A024912(n)+1 = 5*A081759(n)+6.
A104146(floor(a(n)/10)) = 1.
Union of A132230 and A132232. - Ray Chandler, Apr 07 2009
a(n) ~ 4n log n. - Charles R Greathouse IV, Sep 06 2012
Intersection of A000040 and A017281. - Iain Fox, Dec 30 2017

A039949 Primes of the form 30n - 13.

Original entry on oeis.org

17, 47, 107, 137, 167, 197, 227, 257, 317, 347, 467, 557, 587, 617, 647, 677, 797, 827, 857, 887, 947, 977, 1097, 1187, 1217, 1277, 1307, 1367, 1427, 1487, 1607, 1637, 1667, 1697, 1787, 1847, 1877, 1907, 1997, 2027, 2087, 2207, 2237, 2267, 2297, 2357, 2417
Offset: 1

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Author

Keywords

Comments

This linear form produces the most primes for n between 1 and 1000 (411/1000).
Primes congruent to 17 (mod 30). - Omar E. Pol, Aug 15 2007
Primes ending in 7 with (SOD-1)/3 non-integer where SOD is sum of digits. - Ki Punches
Or primes p such that (p mod 3) = (p mod 5) and (p mod 2) <> (p mod 3), (p > 2). - Mikk Heidemaa, Jan 19 2016

References

  • C. Clawson, Mathematical Mysteries, Plenum Press, 1996, p. 173

Crossrefs

Programs

Formula

a(n) = A158648(n)*30 + 17. - Ray Chandler, Apr 07 2009
Intersection of A030432 and A007528. - Ray Chandler, Apr 07 2009
a(n) = A141860(n+1). - Zak Seidov, Apr 15 2015

Extensions

Extended by Ray Chandler, Apr 07 2009

A132236 Primes congruent to 29 (mod 30).

Original entry on oeis.org

29, 59, 89, 149, 179, 239, 269, 359, 389, 419, 449, 479, 509, 569, 599, 659, 719, 809, 839, 929, 1019, 1049, 1109, 1229, 1259, 1289, 1319, 1409, 1439, 1499, 1559, 1619, 1709, 1889, 1949, 1979, 2039, 2069, 2099, 2129, 2309, 2339, 2399, 2459, 2549, 2579
Offset: 1

Views

Author

Omar E. Pol, Aug 15 2007

Keywords

Comments

Primes ending in 9 with (SOD-1)/3 non-integer where SOD is sum of digits. - Ki Punches

Crossrefs

Programs

Formula

a(n) = A158850(n)*30 + 29. - Chandler
Intersection of A030433 and A007528. - Chandler

Extensions

Extended by Ray Chandler, Apr 07 2009

A073102 Primes of the form 210n + 1.

Original entry on oeis.org

211, 421, 631, 1051, 1471, 2311, 2521, 2731, 3361, 3571, 4201, 4621, 4831, 5881, 6091, 6301, 7351, 7561, 8191, 8821, 9241, 9661, 9871, 10501, 10711, 11131, 11551, 11971, 12391, 12601, 13441, 14071, 14281, 15121, 15331, 15541, 16381, 17011
Offset: 1

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Author

Zak Seidov Aug 24 2002

Keywords

Examples

			211 = 210*1 + 1 is prime; 1471 = 210*7 + 1 is prime.
		

Crossrefs

Subsequence of A142076, A124826, and A132230.
Cf. A073085.

Programs

  • Magma
    [ a: n in [0..400] | IsPrime(a) where a is 210*n+1]; // Vincenzo Librandi, Aug 08 2010
    
  • Mathematica
    210*Flatten[Position[PrimeQ[210Range[100]+1], True]]+1
    Select[1+210Range[100],PrimeQ] (* Ray Chandler, Apr 29 2010 *)
  • PARI
    select(x->((x % 210)==1), primes(3000)) \\ Michel Marcus, Jan 14 2018

Extensions

Extended by Ray Chandler, Apr 29 2010

A132231 Primes congruent to 7 (mod 30).

Original entry on oeis.org

7, 37, 67, 97, 127, 157, 277, 307, 337, 367, 397, 457, 487, 547, 577, 607, 727, 757, 787, 877, 907, 937, 967, 997, 1087, 1117, 1237, 1297, 1327, 1447, 1567, 1597, 1627, 1657, 1747, 1777, 1867, 1987, 2017, 2137, 2287, 2347, 2377, 2437, 2467, 2557, 2617, 2647
Offset: 1

Views

Author

Omar E. Pol, Aug 15 2007

Keywords

Comments

Primes ending in 7 with (SOD-1)/3 integer where SOD is sum of digits. - Ki Punches, Feb 07 2009
Intersection of A030432 and A002476. - Ray Chandler, Apr 07 2009
Only from 4927 on, there are more composite numbers than primes in {7+30k}, see A227869. - M. F. Hasler, Nov 02 2013
Terms are non-twin primes A007510, except for 7. - Jonathan Sondow, Oct 27 2017

Crossrefs

Programs

  • Haskell
    a132231 n = a132231_list !! (n-1)
    a132231_list = [x | k <- [0..], let x = 30 * k + 7, a010051' x == 1]
    -- Reinhard Zumkeller, Jul 13 2012
    
  • Magma
    [p: p in PrimesUpTo(3000) | p mod 30 eq 7 ]; // Vincenzo Librandi, Aug 14 2012
    
  • Mathematica
    Select[30*Range[0,100]+7,PrimeQ] (* Harvey P. Dale, Feb 01 2012 *)
    Select[Prime[Range[1000]],MemberQ[{7},Mod[#,30]]&] (* Vincenzo Librandi, Aug 14 2012 *)
  • PARI
    forstep(p=7,1999,30,isprime(p)&&print1(p",")) \\ M. F. Hasler, Nov 02 2013

Formula

a(n) = A158573(n)*30 + 7. - Ray Chandler, Apr 07 2009
a(n) = A211890(4,n-1) for n <= 5. - Reinhard Zumkeller, Jul 13 2012

Extensions

Extended by Ray Chandler, Apr 07 2009

A132232 Primes congruent to 11 (mod 30).

Original entry on oeis.org

11, 41, 71, 101, 131, 191, 251, 281, 311, 401, 431, 461, 491, 521, 641, 701, 761, 821, 881, 911, 941, 971, 1031, 1061, 1091, 1151, 1181, 1301, 1361, 1451, 1481, 1511, 1571, 1601, 1721, 1811, 1871, 1901, 1931, 2081, 2111, 2141, 2351, 2381, 2411, 2441, 2531
Offset: 1

Views

Author

Omar E. Pol, Aug 15 2007

Keywords

Crossrefs

Programs

Formula

From Ray Chandler, Apr 07 2009: (Start)
a(n) = A158614(n)*30 + 11.
Intersection of A030430 and A007528. (End)

Extensions

Extended by Ray Chandler, Apr 07 2009

A132235 Primes congruent to 23 (mod 30).

Original entry on oeis.org

23, 53, 83, 113, 173, 233, 263, 293, 353, 383, 443, 503, 563, 593, 653, 683, 743, 773, 863, 953, 983, 1013, 1103, 1163, 1193, 1223, 1283, 1373, 1433, 1493, 1523, 1553, 1583, 1613, 1733, 1823, 1913, 1973, 2003, 2063, 2153, 2213, 2243, 2273, 2333, 2393
Offset: 1

Views

Author

Omar E. Pol, Aug 15 2007

Keywords

Comments

Primes (excluding 3) ending in 3 with (SOD-1)/3 non-integer where SOD is sum of digits. - Ki Punches
The sequence is infinite by Dirichlet's theorem. - Arkadiusz Wesolowski, Apr 02 2014
Terms are non-twin primes A007510. - Omar E. Pol, Jul 25 2019

Crossrefs

Programs

Formula

a(n) = A158791(n)*30 + 23. - Ray Chandler, Apr 07 2009
Intersection of A030431 and A007528. - Ray Chandler, Apr 07 2009

Extensions

Extended by Ray Chandler, Apr 07 2009

A111175 Numbers n such that 30*n + 1 is prime.

Original entry on oeis.org

1, 2, 5, 6, 7, 8, 9, 11, 14, 18, 19, 20, 21, 22, 23, 25, 27, 33, 34, 35, 39, 40, 41, 43, 44, 46, 49, 51, 54, 58, 60, 61, 62, 65, 67, 71, 72, 74, 75, 76, 77, 78, 79, 84, 85, 89, 91, 93, 95, 99, 100, 102, 104, 106, 109, 110, 111, 112, 113, 117, 118, 119, 121, 123, 131, 134, 135
Offset: 1

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Author

Parthasarathy Nambi, Oct 21 2005

Keywords

Comments

Encoded primes with LSD 1 and (SOD-1)/3 integer, (LSD, least significant digit; SOD, sum of digits). Divide any such number by 30, if the whole number portion of the quotient is in the sequence, the number is prime. Example: 2671, with LSD 1 and (SOD-1)/3 = 2 (integer); Then 2671/30 = 89.033, or 89, which is in the sequence, and thus 2671 is prime. - Ki Punches, Mar 18 2009

Examples

			If n=99 then 30*n + 1 = 2971 (prime).
		

Crossrefs

Programs

Formula

a(n) = (A132230(n) - 1)/30 = Floor[A132230(n)/30]. - Chandler

Extensions

Extended by Ray Chandler, Apr 07 2009

A132233 Primes congruent to 13 (mod 30).

Original entry on oeis.org

13, 43, 73, 103, 163, 193, 223, 283, 313, 373, 433, 463, 523, 613, 643, 673, 733, 823, 853, 883, 1033, 1063, 1093, 1123, 1153, 1213, 1303, 1423, 1453, 1483, 1543, 1663, 1693, 1723, 1753, 1783, 1873, 1933, 1993, 2053, 2083, 2113, 2143, 2203, 2293, 2383
Offset: 1

Views

Author

Omar E. Pol, Aug 15 2007

Keywords

Comments

Primes ending in 3 with (SOD-1)/3 integer where SOD is sum of digits. - Ki Punches
Subsequence of primes of A082369. - Michel Marcus, Jan 23 2016

Crossrefs

Programs

  • Magma
    [p: p in PrimesUpTo(3000) | p mod 30 eq 13 ]; // Vincenzo Librandi, Aug 14 2012
    
  • Maple
    select(isprime, [seq(30*i+13,i=0..1000)]); # Robert Israel, Jan 24 2016
  • Mathematica
    Select[Prime[Range[1000]],MemberQ[{13},Mod[#,30]]&] (* Vincenzo Librandi, Aug 14 2012 *)
  • PARI
    lista(nn) = forprime(p=2, nn, if(p % 30 == 13, print1(p, ", "))); \\ Altug Alkan, Jan 23 2016

Formula

a(n) = A158746(n)*30 + 13. - Ray Chandler, Apr 07 2009
Intersection of A030431 and A002476. - Ray Chandler, Apr 07 2009

Extensions

Extended by Ray Chandler, Apr 07 2009

A132234 Primes congruent to 19 (mod 30).

Original entry on oeis.org

19, 79, 109, 139, 199, 229, 349, 379, 409, 439, 499, 619, 709, 739, 769, 829, 859, 919, 1009, 1039, 1069, 1129, 1249, 1279, 1399, 1429, 1459, 1489, 1549, 1579, 1609, 1669, 1699, 1759, 1789, 1879, 1999, 2029, 2089, 2179, 2239, 2269, 2389, 2539, 2659, 2689
Offset: 1

Views

Author

Omar E. Pol, Aug 15 2007

Keywords

Comments

Also primes congruent to 4 (mod 15). - N. J. A. Sloane, Jul 11 2008
Primes ending in 9 with (SOD-1)/3 integer where SOD is sum of digits. - Ki Punches

Crossrefs

Programs

Formula

a(n) = A158806(n)*30 + 19. - Chandler
Intersection of A030433 and A002476. - Chandler

Extensions

Extended by Ray Chandler, Apr 07 2009
Showing 1-10 of 21 results. Next