OFFSET
1,1
COMMENTS
A divisorial prime is a prime p of the form p = 1 + Product_{d|k} d for some k (see A007955 and A258455).
Sequence lists divisorial primes p of the form h*10^m + 1 (h, m are positive integers).
Sequence of numbers sqrt(a(n) - 1): 10, 184900, 504100, 532900, 1612900, 3648100, 6300100, 7236100, 7672900, ...
Sequence of numbers k such that 1 + Product_{d|k} d is a divisorial prime ending with digit 1: 10, 430, 510, 680, 710, 730, ...
LINKS
Chai Wah Wu, Table of n, a(n) for n = 1..145
FORMULA
Subsequence of A258455.
EXAMPLE
Prime 34188010001 is in sequence because 34188010000 is the product of divisors of 430.
1 + the product of divisors of 3000 = 43046721000000000000000000000000000000000000000000000001 is also a term of this sequence.
PROG
(Magma) Set(Sort([&*(Divisors(n))+1: n in [1..10000] | IsSquare(&*(Divisors(n))) and IsPrime(&*(Divisors(n))+1) and (&*(Divisors(n))) mod 10 eq 0]))
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Jaroslav Krizek, Jun 20 2015
STATUS
approved