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.

Previous Showing 21-27 of 27 results.

A078947 Primes p such that the differences between the 5 consecutive primes starting with p are (2,4,6,6).

Original entry on oeis.org

41, 641, 1091, 4001, 9461, 26681, 26711, 44531, 79811, 103991, 110921, 112571, 172421, 223241, 276821, 289841, 290021, 317771, 373181, 381371, 434921, 450881, 493121, 602081, 678761, 788351, 834131, 907211, 974861, 1076501, 1081121, 1097891, 1200371, 1409531, 1426151
Offset: 1

Views

Author

Labos Elemer, Dec 19 2002

Keywords

Comments

Equivalently, primes p such that p, p+2, p+6, p+12 and p+18 are consecutive primes.

Examples

			641 is in the sequence since 641, 643 = 641 + 2, 647 = 641 + 6, 653 = 641 + 12 and 659 = 641 + 18 are consecutive primes.
		

Crossrefs

Programs

  • Mathematica
    Select[Partition[Prime[Range[50000]], 5, 1], Differences[#] == {2, 4, 6, 6} &][[;;, 1]] (* Amiram Eldar, Feb 21 2025 *)
  • PARI
    list(lim) = {my(p1 = 2, p2 = 3, p3 = 5, p4 = 7); forprime(p5 = 11, lim, if(p2 - p1 == 2 && p3 - p2 == 4 && p4 - p3 == 6 && p5 - p4 == 6, print1(p1, ", ")); p1 = p2; p2 = p3; p3 = p4; p4 = p5);} \\ Amiram Eldar, Feb 21 2025

Formula

a(n) == 11 (mod 30). - Amiram Eldar, Feb 21 2025

Extensions

Edited by Dean Hickerson, Dec 20 2002

A286891 Initial primes of 6 consecutive primes with 5 consecutive gaps 10, 8, 6, 4, 2.

Original entry on oeis.org

41203, 556243, 576193, 715849, 752263, 859249, 891799, 1107763, 1191079, 1201999, 1210369, 1510189, 1601599, 1893163, 2530963, 2678719, 2881243, 3257689, 3431479, 3545263, 3792949, 3804919, 4041109, 4479463, 4867309
Offset: 1

Views

Author

Muniru A Asiru, Jul 22 2017

Keywords

Comments

All terms = {13,19} mod 30.
For initial primes of 6 consecutive primes with consecutive gaps 2, 4, 6, 8, 10 see A190817.

Examples

			Prime(4313..4318) = {41203, 41213, 41221, 41227, 41231, 41233} and 41203 + 10 = 41213, 41213 + 8 = 41221, 41221 + 6 = 41227, 41227 + 4 = 41231, 41231 + 2 = 41233.
Also, prime(68287..68292) = {859249, 859259, 859267, 859273, 859277, 859279} and 859249 + 10 = 859259, 859259 + 8 = 859267, 859267 + 6 = 859273, 859273 + 4 = 859277, 859277 + 2 = 859279.
		

Crossrefs

Programs

  • GAP
    P:=Filtered([1..20000000],IsPrime);;  I:=Reversed([2,4,6,8,10]);;
    P1:=List([1..Length(P)-1],i->P[i+1]-P[i]);;
    P2:=List([1..Length(P)-Length(I)],i->[P1[i],P1[i+1],P1[i+2],P1[i+3],P1[i+4]]);;
    P3:=List(Positions(P2,I),i->P[i]);
  • Maple
    K:=10^7: # to get all terms <= K.
    Primes:=select(isprime,[seq(i,i=3..K+30,2)]): Primes[select(t->[Primes[t+1]-Primes[t], Primes[t+2]-Primes[t+1], Primes[t+3]-Primes[t+2], Primes[t+4]-Primes[t+3], Primes[t+5]-Primes[t+4]]=[10,8,6,4,2], [$1..nops(Primes)-5])]; # Muniru A Asiru, Aug 15 2017
  • Mathematica
    Select[Partition[Prime[Range[340000]],6,1],Differences[#]=={10,8,6,4,2}&][[All,1]] (* Harvey P. Dale, Aug 22 2018 *)

A079017 Suppose p and q = p+14 are primes. Define the difference pattern of (p,q) to be the successive differences of the primes in the range p to q. There are 15 possible difference patterns, namely [14], [2,12], [6,8], [8,6], [12,2], [2,4,8], [2,6,6], [2,10,2], [6,2,6], [6,6,2], [8,4,2], [2,4,6,2], [2,6,4,2], [2,2,4,2,4], [2,4,2,4,2]. Sequence gives smallest value of p for each difference pattern, sorted by magnitude.

Original entry on oeis.org

3, 5, 17, 23, 29, 47, 83, 89, 113, 137, 149, 197, 359, 509, 1997
Offset: 1

Views

Author

Labos Elemer, Jan 24 2003

Keywords

Examples

			p=1997, q=2011 has difference pattern [2,4,8] and {1997,1999,2003,2011} is the corresponding consecutive prime 4-tuple.
		

Crossrefs

A022006(1)=5, A022007(1)=7, A078847(1)=17, A078851(1)=19, A078946(1)=17, A078854(1)=23, A078948(1)=29, A078857(1)=47, A031932(1)=113, A078849(1)=149.

A281448 Initial primes of 9 consecutive primes with consecutive gaps 2, 4, 6, 8, 10, 12, 14, 16.

Original entry on oeis.org

113575727, 232728647, 2426256797, 2469604721, 3344410367, 4656098957, 4952808461, 6369321857, 6430890287, 6760087151, 8518049207, 10818813737, 13195845317, 19684555061, 21884908931, 23953276661, 25509639137, 26367829331, 26390212061, 31004257211
Offset: 1

Views

Author

Harvey P. Dale, Jan 27 2017

Keywords

Crossrefs

Programs

  • Mathematica
    Select[Partition[Prime[Range[20*10^7]], 9, 1], Differences[#] == 2*Range[8] &][[All, 1]]
  • PARI
    g=0; p=2; forprime(q=3,, if(q-p==g+2, g+=2; if(g==16, print1(q-72", "); g=0), g=0); p=q) \\ Charles R Greathouse IV, Jan 28 2017

Extensions

a(10)-a(20) from Charles R Greathouse IV, Jan 28 2017

A289907 Initial primes of 5 consecutive primes with consecutive gaps 8,6,4,2.

Original entry on oeis.org

1979, 5399, 11813, 41213, 42443, 44249, 47129, 55799, 57773, 74699, 79613, 84299, 88643, 126473, 143813, 148913, 167099, 176489, 178799, 178889, 209249, 211859, 237143, 266663, 267629, 272249, 272333, 322229, 344153, 348443, 354023, 375083, 391379, 399263, 422069, 449549, 521519, 529673
Offset: 1

Views

Author

Muniru A Asiru, Jul 14 2017

Keywords

Comments

All terms = {23, 29} mod 30.
For initial primes of 5 consecutive primes with consecutive gaps 2,4,6,8 see A190814.
Number of terms less than 10^k: 0, 0, 0, 2, 13, 65, 317, 1563, 8671, 50643, ..., . - Robert G. Wilson v, Dec 07 2017

Examples

			Prime(299..303) = { 1979, 1987, 1993, 1997, 1999 } and 1979 + 8 = 1987, 1987 + 6 = 1993, 1993 + 4 = 1997, 1997 + 2 = 1999.
Also, prime(5852..5856) = { 57773, 57781, 57787, 57791, 57793 } and 5773 + 8 = 57781, 57781 + 6 = 57787, 57787 + 4 = 57791, 57791 + 2 = 57793.
		

Crossrefs

Programs

  • GAP
    I:=[8,6,4,2];;
    P:=Filtered([1..1000000],IsPrime);;
    P1:=List([1..Length(P)-1],i->P[i+1]-P[i]);;  Collected(last);;
    P2:=List([1..Length(P)-Length(I)],i->[P1[i],P1[i+1],P1[i+2],P1[i+3]]);;
    P3:=List(Positions(P2,I),i->P[i]);
    
  • Mathematica
    s = Prepend[Differences@ #, First@ #] & /@ Partition[Prime@ Range[10^5], 5, 1]; Select[s, Drop[#, 1] == Range[8, 2, -2] &][[All, 1]] (* Michael De Vlieger, Jul 14 2017 *)
    p = {2, 3, 5, 7, 11}; lst = {}; While[ p[[1]] < 530000, If[ Differences@ p == {8, 6, 4, 2}, AppendTo[ lst, p[[1]] ]]; p = Join[Rest@ p, {NextPrime[ p[[-1]]] }]]; lst (* Robert G. Wilson v, Dec 07 2017 *)
  • PARI
    is(n) = my(q); forstep(i=8,2,-2,q=nextprime(n+1); if(q-n!=i,return(0)); n=q); return(1) \\ David A. Corneth, Jul 23 2017

A290264 Initial primes of 9 consecutive primes with 8 consecutive gaps 16, 14, 12, 10, 8, 6, 4, 2.

Original entry on oeis.org

32465047, 37091581, 146742847, 239659891, 245333251, 272213797, 1060690651, 1541736811, 2002738207, 2480351677, 2636566351, 4421955007, 6168859201, 8158683037, 10367633527, 10623394321, 11452116817, 11691059641, 11892876841, 13551877831, 15043908637
Offset: 1

Views

Author

Muniru A Asiru, Jul 25 2017

Keywords

Comments

All terms = {1,7} mod 30.
For initial primes of 7 consecutive primes with 6 consecutive gaps 12, 10, 8, 6, 4, 2 and 8 consecutive primes with 7 consecutive gaps 14, 12, 10, 8, 6, 4, 2 see A290161 and A290162 respectively.
a(6) > 250000000.

Examples

			32465047 is a member of this sequence because the 9 consecutive primes 32465047, 32465063, 32465077, 32465089, 32465099, 32465107, 32465113, 32465117, 32465119 have consecutive gaps 16, 14, 12, 10, 8, 6, 4, 2. That is, 32465047 + 16 = 32465063, 32465063 + 14 = 32465077, 32465077 + 12 = 32465089, 32465089 + 10 = 32465099, 32465099 + 8 = 32465107, 32465107 + 6 = 32465113, 32465113 + 4 = 32465117, 32465117 + 2 = 32465119.
		

Crossrefs

Programs

  • GAP
    P:=Filtered([1..50000000],IsPrime);;I:=Reversed([2,4,6,8,10,12,14,16]);;
    P1:=List([1..Length(P)-1],i->P[i+1]-P[i]);;  Collected(last);;
    P2:=List([1..Length(P)-Length(I)],i->[P1[i],P1[i+1],P1[i+2],P1[i+3],P1[i+4],P1[i+5],P1[i+6],P1[i+7]]);;
    P3:=List(Positions(P2,I),i->P[i]); Length(P3);

Extensions

a(6)-a(21) from Giovanni Resta, Jul 25 2017

A290706 Greatest of 4 consecutive primes with consecutive gaps 2, 4, 6.

Original entry on oeis.org

29, 53, 239, 359, 653, 1103, 1289, 1439, 1499, 1619, 2699, 3539, 3929, 4013, 4139, 4649, 4799, 4943, 8243, 9473, 10343, 11789, 12119, 13913, 14639, 20759, 21569, 23753, 25589, 26693, 26723, 27749, 27953, 28289, 29033, 31259
Offset: 1

Views

Author

Muniru A Asiru, Aug 09 2017

Keywords

Comments

All terms = {23, 29} mod 30.

Examples

			29 is a member of the sequence because 29 is the greatest of the 4 consecutive primes 17, 19, 23, 29 with consecutive gaps 2, 4, 6.
		

Crossrefs

Programs

  • GAP
    K:=3*10^7+1;; # to get all terms <= K.
    P:=Filtered([1,3..K],IsPrime);;    I:=[2,4,6];;
    P1:=List([1..Length(P)-1],i->P[i+1]-P[i]);;
    P2:=List([1..Length(P)-Length(I)],i->[P1[i],P1[i+1],P1[i+2]]);;
    P3:=List(Positions(P2,I),i->P[i+Length(I)]);
  • Maple
    for i from 1 to 10^5 do if ithprime(i+1)=ithprime(i)+2 and ithprime(i+2)=ithprime(i)+6 and ithprime(i+3)=ithprime(i)+12 then print(ithprime(i+3)); fi; od;
  • Mathematica
    Select[Prime@ Range@ 3500, NextPrime[#, {1, 2, 3}] == # + {2, 6, 12} &] + 12 (* Giovanni Resta, Aug 09 2017 *)

Formula

a(n) = A078847(n) + 12.
Previous Showing 21-27 of 27 results.