A085344 Least number x such that number of primes between sigma(x) and x equals n.

2, 4, 10, 12, 16, 46, 28, 24, 44, 30, 42, 40, 36, 54, 48, 66, 178, 78, 104, 80, 102, 60, 128, 72, 84, 152, 90, 138, 255, 96, 108, 174, 140, 126, 132, 266, 160, 150, 248, 222, 156, 120, 246, 200, 144, 198, 634, 224, 220, 204, 370, 260, 168, 376, 555, 430, 354, 308

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

a(n) = Min{x; A085341(x)=n}.

Mathematica

m = 100; seq = Table[0, {m}]; c = 0; n = 0; While[c < m, n++; i = PrimePi[ DivisorSigma[1, n]] - PrimePi[n]; If[i <= m && seq[[i]] == 0, c++; seq[[i]] = n]]; seq (* Amiram Eldar, Mar 01 2020 *)

Prog

(PARI) a(n) = {my(x=1); while (primepi(sigma(x)) - primepi(x) != n, x++); x; } \\ Michel Marcus, Mar 01 2020

Crossrefs

Cf. A000720, A000010, A000203, A070803, A070804.

Cf. A085341, A085342, A085343, A085345, A085346, A085347.

Sequence in context: A266115 A113536 A081887 * A288225 A047463 A107059

Adjacent sequences: A085341 A085342 A085343 * A085345 A085346 A085347

Keyword

nonn

Author

Labos Elemer, Jul 10 2003

Status

approved