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 1-3 of 3 results.

A290162 Initial primes of 8 consecutive primes with 7 consecutive gaps 14, 12, 10, 8, 6, 4, 2.

Original entry on oeis.org

5647457, 18117977, 21705503, 32465063, 37091597, 57269633, 90217163, 109933673, 111053573, 124123133, 145594583, 146742863, 163123997, 200416343, 239659907, 245333267, 272213813, 335971367, 350795033, 470838833, 701465327, 749927357, 888801707, 1060690667
Offset: 1

Views

Author

Muniru A Asiru, Jul 22 2017

Keywords

Comments

All terms = {17,23} mod 30.
For initial primes of 8 consecutive primes with consecutive gaps 2, 4, 6, 8, 10, 12, 14 see A190838.

Examples

			Prime(390215..390222) = {5647457, 5647471, 5647483, 5647493, 5647501, 5647507, 5647511, 5647513} and 5647457 + 14 = 5647471, 5647471 + 12 = 5647483, 5647483 + 10 = 5647493, 5647493 + 8 = 5647501, 5647501 + 6 = 5647507, 5647507 + 4 = 5647511, 5647511 + 2 = 5647513.
		

Crossrefs

Programs

  • GAP
    P:=Filtered([1..100000000],IsPrime);; I:=Reversed([2,4,6,8,10,12,14]);;
    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]]);;
    P3:=List(Positions(P2,I),i->P[i]); Length(P3);

Extensions

a(8)-a(24) from Giovanni Resta, Jul 25 2017

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 *)

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
Showing 1-3 of 3 results.