A361492 Common difference corresponding to increasing arithmetic progression of at least n >= 2 primes whose first term is A284708(n); a(1) = 1.
1, 1, 2, 6, 30, 30, 210, 210, 210, 17430, 30030, 60060, 510510, 3573570
Offset: 1
Examples
Common difference and corresponding n primes in arithmetic progression. a(1) = 1: (2); a(2) = 1: (2, 3); a(3) = 2: (3, 5, 7); a(4) = 6: (11, 17, 23, 29); a(5) = 30: (37, 67, 97, 127, 157); a(6) = 30: (107, 137, 167, 197, 227, 257); a(7) = 210: (409, 619, 829, 1039, 1249, 1459, 1669); a(8) = 210: (409, 619, 829, 1039, 1249, 1459, 1669, 1879); a(9) = 210: (409, 619, 829, 1039, 1249, 1459, 1669, 1879, 2089);
References
- David Wells, The Penguin Dictionary of Curious and Interesting Numbers, Revised Edition, Penguin Books, London, England, 1997, entry 11410337850553, page 191.
Crossrefs
Cf. A284708.
Programs
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PARI
isokd(p, n, d) = for (i=1, n, if (!isprime(p+(i-1)*d), return(0))); 1; isokp(p, n) = for (d=1, p-1, if (isokd(p, n, d), return(d));); a(n) = my(p=2, d); while (!(d=isokp(p, n)), p=nextprime(p+1)); d; \\ Michel Marcus, Mar 16 2023
Comments