20201019, 15:45  #1 
Nov 2016
2^{2}×691 Posts 
757
757 is irregular prime
757 is de Polignac number (cannot be written as 2^n+p with prime p) 757 is the smallest prime p such that 1/p has period length 3^3 (in decimal) The smallest n such that Phi_n(k,k1) is prime is 414, where k is 757 (this is the largest for k<=1024) (there are only 3 nvalues <=1024 such that Phi_n(k,k1) is prime, and both of them are even, where k is 757) (if we require n is prime, then the smallest n is 96487) There is no known prime of the form (b1)*b^n+1 with n>=1, where b is 757 The smallest known prime of the form b*(b+1)^n1 is very large, where b is 757 
20201019, 20:33  #2 
"Viliam FurÃk"
Jul 2018
Martin, Slovakia
2^{3}×41 Posts 

20201101, 23:22  #4 
"Daniel Jackson"
May 2011
14285714285714285714
631 Posts 
www.numbersaplenty.com/757
If you click on one of the categories (i.e. strong prime), it has links to OEIS and Wikipedia at the bottom of the page (under Useful Links), so the information is correct (unless the linked sequence and/or Wiki page is in error). I'm sure that's where Sweety439 is getting that info. 