This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A321510 Primes p for which there exists a prime q < p such that 3*q == 1 (mod p). 1
 5, 7, 19, 43, 61, 79, 109, 151, 163, 223, 271, 349, 421, 439, 523, 601, 613, 631, 673, 691, 811, 853, 919, 991, 1009, 1051, 1063, 1153, 1213, 1231, 1279, 1321, 1429, 1531, 1549, 1663, 1693, 1789, 1801, 1873, 1933, 1951, 2113, 2143, 2179, 2221, 2239, 2503, 2539, 2683, 2791, 2833, 2851 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A104163 with 5 prepended (see example). For any prime p in A104163 q = (2*p+1)/3, then q < p and 3*q == 1 (mod p). LINKS FORMULA a(n+1) = A104163(n); n >= 1. EXAMPLE For p = 11, the only number t < 11 such that 3*t == 1 (mod 11) is t = 4, which is not prime, therefore 11 is not a term. For p = 5, q = 2 (prime); 2*3 = 6 == 1 (mod 5) therefore 5 is a term. MAPLE for n from 3 to 300 do Y := ithprime(n); Z := 1/3 mod Y; if isprime(Z) then print(Y); end if: end do: MATHEMATICA aQ[p_]:=Module[{ans=False, q=2}, While[q

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified August 24 14:11 EDT 2019. Contains 326282 sequences. (Running on oeis4.)