A320712 Indices of primes followed by a gap (distance to next larger prime) of 28.

429, 462, 685, 781, 1116, 1231, 1274, 1288, 1327, 1392, 1585, 1708, 1710, 1891, 1944, 2065, 2154, 2367, 2417, 2606, 2663, 2729, 2980, 3012, 3069, 3227, 3519, 3653, 3990, 4018, 4168, 4196, 4595, 4603, 4618, 4797, 4856, 4867, 5123, 5191, 5294, 5375, 5432, 5476, 5498, 5593, 5627, 5688, 5703

Offset

1,1

Comments

Indices of the primes listed in A124595.

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Index entries for primes, gaps between.

Formula

a(n) = A000720(A124595(n)).

A320712 = { i > 0 | prime(i+1) = prime(i) + 28 }.

Maple

P:= select(isprime, [2, seq(i, i=3..10^5, 2)]): nP:= nops(P):
DP:= P[2..-1]-P[1..-2]:
select(t -> DP[t]=28, [$1..nP-1]); # Robert Israel, Mar 18 2026

Prog

(PARI) A(N=100, g=28, p=2, i=primepi(p)-1, L=List())={forprime(q=1+p, , i++; if(p+g==p=q, listput(L, i); N--||break)); Vec(L)} \\ returns the list of first N terms of the sequence

Crossrefs

Equals A000720 o A124595.

Indices of 28's in A001223.

Row 14 of A174349.

Cf. A029707, A029709, A320701, A320702, ..., A320720 (analog for gaps 2, 4, 6, 8, ..., 44), A116493 (gap 70), A116496 (gap 100), A116497 (gap 200), A116495 (gap 210).

Sequence in context: A177328 A243833 A334558 * A338344 A203612 A250330

Adjacent sequences: A320709 A320710 A320711 * A320713 A320714 A320715

Keyword

nonn

Author

M. F. Hasler, Oct 19 2018

Status

approved