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.
103 initiates [103,107,109,113] prime quadruple followed by [4,2,4] difference pattern.
a = {}; Do[If[Prime[x + 3] - Prime[x] == 10, AppendTo[a, Prime[x]]], {x, 1, 10000}]; a (* Zerinvary Lajos, Apr 03 2007 *)
Select[Partition[Prime[Range[3000]],4,1],Differences[#]=={4,2,4}&][[All,1]] (* Harvey P. Dale, Jun 16 2017 *)
is(n)=n%6==1 && isprime(n+4) && isprime(n+6) && isprime(n+10) && isprime(n) \\ Charles R Greathouse IV, Apr 29 2015
1867 is here because the successor primes (1867),1871,1873,1877,1879 give 4242 difference pattern. The primes around this island are 1861 and 1889 in distance 6 and 10 resp. Thus the d-pattern "around 1867" is {6,4,2,4,2,10}. [corrected by _Zak Seidov_, May 07 2017]
m=1867; Reap[Do[While[ PrimeQ[m] m = m + 30]; If[
m > NextPrime[m, -1] + 5 && AllTrue[m + {4, 6, 10, 12}, PrimeQ] && NextPrime[m + 12] > m + 17, Sow[m]]; m = m + 30, {10^5}]][[2, 1]] (* Zak Seidov, May 07 2017 *)
127 is in the sequence because 127 + 4 = 131 is prime, but the difference pattern around 127 is {[113] 14 [127] 4 [131] 6 [137]}.
s = Differences@ Prime@ Range[600]; Prime@ Select[Position[s, 4][[All, 1]], And[s[[# - 1]] >= 6, s[[# + 1]] >= 6] &] (* Michael De Vlieger, Aug 17 2023 *)
The gap of 15960 between sextuplets with initial primes 97 and 16057 is a maximal gap - larger than any preceding gap; therefore a(2)=15960.
DeleteDuplicates[Differences[Select[Partition[Prime[Range[10^7]],6,1],Differences[#]=={4,2,4,2,4}&][[;;,1]]],GreaterEqual] (* The program generates the first 10 terms of the sequence. *) (* Harvey P. Dale, May 08 2025 *)
191 is here because 191 + 2 = 193, 191 + 4 + 2 = 197, 191 + 2 + 4 + 2 = 199 are primes; the prime preceding 191 is 181; the prime following 199 is 211; and the corresponding differences are 10 and 12. Thus the d-pattern "around 191" is {10,2,4,2,12}.
Primes:= select(isprime,[2,seq(i,i=3..10^6,2)]): Gaps:= Primes[2..-1]-Primes[1..-2]: Primes[select(t -> Gaps[t] = 2 and Gaps[t+1] = 4 and Gaps[t+2] = 2 and Gaps[t-1] >= 6 and Gaps[t+3]>=6, [$2..nops(Gaps)-3])]; # Robert Israel, Nov 30 2015
With[{x = 6, y = 6, s = Partition[#, 6, 1] &@ Prime@ Range[3*10^4]}, Select[s, And[First@ # >= x, Last@ # >= y, Most@ Rest@ # == {2, 4, 2}] &@ Differences@ # &]][[All, 2]] (* Michael De Vlieger, Oct 26 2017 *)
59 is here because 59 + 2 = 61 is prime, but the difference pattern around 59 is {[53] 6 [59] 2 [61] 6 [67]}.
Select[Prime@ Range[2, 500], Times @@ Boole@ {First@ # >= 6, #[[2]] == 2, Last@ # >= 6} == 1 &@ Differences@ Prime[# + Range[-1, 2]] &@ PrimePi@ # &] (* Michael De Vlieger, Jul 04 2016 *)
641 is in the sequence because 641 + 2 = 643, 641 + 2 + 4 = 647 is prime, the prime prior to 641 is 631, the prime after 647 is 653, and the corresponding differences are 10 or 6. The d-pattern is {10,2,4,6}.
37 is here because 37 + 4 = 41, 37 + 4 + 2 = 43, 37 + 4 + 2 + 4 = 47 are consecutive primes and the prime preceding 37 is 31, the prime following 47 is 53, and the corresponding differences are 6 and 6. Thus the d-pattern "around 37" is {6,4,2,4}.
okQ[n_List]:=Module[{d=Differences[n]},Take[d,{2,4}]=={4,2,4} && First[d]>5&&Last[d]>5]; Transpose[Select[ Partition[ Prime[ Range[ 4400]], 6, 1],okQ]][[2]] (* Harvey P. Dale, Jul 17 2011 *)
21011 is here because 21011+{2,2+4,2+4+2,2+4+2+4}=21011+{1,6,8,12}= {21013,21013,21017,21019,21023} are consecutive primes but the primes in the immediate neighborhood (21001 and 21031) are in distance 10 and 8. Thus the d-pattern "around 21011" is {10,2,4,2,4,12}.
patQ[n_]:=Module[{d=Differences[n]},First[d]>5&&Last[d]>5&&Most[ Rest[d]] == {2,4,2,4}]; Transpose[Select[Partition[Prime[ Range[ 80000]],7,1],patQ]] [[2]] (* Harvey P. Dale, Dec 11 2013 *)
Comments