A259020 Numbers k such that k^2 + 1 is a divisorial prime (A258455).

1, 6, 10, 14, 26, 74, 94, 134, 146, 206, 314, 326, 386, 466, 576, 634, 674, 1094, 1174, 1294, 1306, 1354, 1366, 1546, 1654, 1766, 1774, 1894, 1966, 2026, 2126, 2174, 2326, 2594, 2654, 2746, 2916, 2974, 2986, 3046, 3106, 3134, 3136, 3214, 3254, 3274, 3314, 3326

Offset: 1

Author

Jaroslav Krizek, Sep 01 2015

Keywords

• nonn

Comments

The divisorial primes are primes of the form p = 1 + Product_{d|k} d = 1 + A007955(k) for some k.

Supersequence of A259021. Subsequence of A005574. First deviation from A259021 is at a(15).

Examples

			The number 6 is in sequence because prime 37 = 6^2 + 1 is prime of the form p = 1 + Product_{d|k} d = 1 + A007955(k) for k = 6.
		

Links

• OEIS wiki, Divisorial primes

Crossrefs

Cf. A005574, A007955, A048943, A118369, A258455, A258897, A259021, A259023.

Programs

Magma

Set(Sort([1] cat [Floor(Sqrt(&*(Divisors(n)))): n in [3..10000] | IsPrime(&*(Divisors(n))+1)]));