A336966
Primes starting 10-tuples of consecutive primes that have symmetrical gaps about their mean and form 5 pairs of twin primes.
Original entry on oeis.org
3031329797, 5188151387, 14168924459, 14768184029, 18028534367, 26697800819, 26919220961, 29205326387, 32544026699, 39713433671, 45898528799, 48263504459, 50791655009, 66419473031, 71525244611, 80179195037, 83700877199, 86767580069, 97660776137, 108116163479
Offset: 1
a(1) = A274792(5) = 3031329797 starts a 10-tuple of consecutive primes: 3031329797+s for s in {0, 2, 12, 14, 42, 44, 72, 74, 84, 86} that are symmetric about 3031329797+43 and form 5 pairs of twin primes.
A333977
Prime starting a sequence of 20 consecutive primes with symmetrical gaps about the center.
Original entry on oeis.org
1797595814863, 2375065608481, 4465545586753, 21818228348093, 67696772430071, 82116093014611, 155947272322087, 161980267642951, 169560139541641, 202619277419161, 285719200081877, 299828814652799, 314942862282899, 365706921997577
Offset: 1
Cf.
A000040,
A055381,
A055382,
A064101,
A081235,
A175309,
A335044,
A335394,
A336967,
A336968,
A359440.
A263171
Smallest prime starting a sequence of 4 consecutive odd primes such that the center of the symmetrical gaps is 2n.
Original entry on oeis.org
7, 5, 251, 353, 137, 2393, 109, 1931, 1753, 883, 3733, 7351, 12007, 2969, 8887, 27697, 1321, 22811, 38377, 62987, 183823, 15679, 124001, 180563, 45887, 48677, 100847, 178693, 152993, 557087, 34057, 367949, 294551, 134507, 173357, 1802407, 531359, 1134311, 933067
Offset: 1
a(2)=5 because the 4 consecutive primes 5, 7, 11, 13 have gaps 2, 4, 2, which is symmetric about its center 4 = 2*2.
-
with(numtheory):nn:=500000:l:=2:T:=array(1..2*l-1)):
for n from 1 to 35 do:ii:=0:
for k from 1 to nn while(ii=0) do:
lst:={}:lst1:={}:
for m from 1 to 2*l do:
lst:=lst union {ithprime(k+m-1)}
od:
for p from 1 to 2*l do:
lst1:=lst1 union {lst[p]+lst[2*l-p+1]}
od:
n0:=nops(lst1):
if n0=1
then
for a from 1 to 2*l-1 do:
T[a]:=lst[a+1]-lst[a]:
od:
if T[2]=2*n then ii:=1:printf(`%d, `,lst[1]):
else fi :fi:
od :
od:
-
a(n) = {pa = 3; pb = 5; pc = 7; forprime(p=8, , if (((pc-pb) == 2*n) && ((pb-pa) == (p-pc)), return(pa)); pa = pb; pb = pc; pc = p;);} \\ Michel Marcus, Oct 16 2015
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