A051902 Minimal primorial safe primes: p and primorial*p + 1 are both primes.

5, 13, 61, 421, 4621, 150151, 8678671, 106696591, 2454021571, 71166625531, 401120980261, 170676977100631, 2129751844690471, 562558737261811291, 11682905869181336791, 97767475431570134191, 9613801750771063195351

Offset

1,1

Comments

In A051888, 13 of the first 25 values are distinct, while here all corresponding min-primorial-safe-primes are different: {2,5,17,11,23,43,19,3,7,61,53,41,47}.

Links

Table of n, a(n) for n=1..17.

Formula

a(n) = 1 + A002110(n)*A051887(n).

Example

The first five terms of A051887 are 2, so the first 5 terms have the form 1 + 2*A002110(n): 5, 13, 61, 421, 4621, which are smallest terms in A005385, A051644, A051646, A051648, A051649. The 6th term here is A051651(1) = A051887(6)*A002110(6) + 1 = 5*30030 + 1.

Crossrefs

Cf. A005385, A002110, A051644, A051646, A051648, A051649.

Sequence in context: A149568 A201805 A144725 * A269514 A149569 A149570

Adjacent sequences: A051899 A051900 A051901 * A051903 A051904 A051905

Keyword

nonn

Author

Labos Elemer, Dec 16 1999

Status

approved