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Primes p such that prime(p-1) mod (p-1) = (prime(p) mod p) - 1.
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%I #23 Feb 16 2021 01:03:18

%S 2,3,13,23,97,101,103,109,131,457,641,677,751,787,811,881,977,1019,

%T 1049,2719,2753,2777,2909,3067,3083,3203,3329,3331,3547,3557,3613,

%U 3767,3823,3833,3847,3911,3929,4007,4159,4219,4259,4327,4421,4591,4639

%N Primes p such that prime(p-1) mod (p-1) = (prime(p) mod p) - 1.

%C Primes p such that A004648(p-1) + 1 = A004648(p).

%e 2 is a term because 2 is prime and A004648(2-1) = A004648(2)-1 = 0.

%o (Sage) A004648 = lambda n: nth_prime(n) % n

%o is_A177746 = lambda n: is_prime(n) and A004648(n) == A004648(n-1)+1 # _D. S. McNeil_, Dec 12 2010

%o (PARI) s=[]; forprime(n=2, 5000, if(prime(n-1)%(n-1) == prime(n)%n-1, s=concat(s, n))); s \\ _Colin Barker_, Jun 27 2014

%Y Cf. A000040, A004648.

%K nonn,less

%O 1,1

%A _Juri-Stepan Gerasimov_, Dec 12 2010

%E Corrected and extended by _D. S. McNeil_, Dec 12 2010