A076192 n == 1 mod 10 with property that n through n+9 contain no primes.

201, 321, 511, 531, 621, 841, 891, 1071, 1131, 1141, 1261, 1331, 1341, 1351, 1411, 1461, 1501, 1641, 1671, 1681, 1711, 1761, 1791, 1851, 1891, 1921, 1961, 2041, 2071, 2101, 2181, 2191, 2321, 2361, 2401, 2481, 2491, 2511, 2561, 2581, 2821, 2941, 2981

Offset

1,1

Comments

Since a decade of consecutive numbers may contain up to 4 primes, more precisely a prime quadruple(p, p+2, p+6, p+8) within a decade k through k+9, where k=p-1 or p (=A007530) excepting the first case (2, 3, 5, 7), this sequence may be regarded as a counterpart to A007530.

Equals A078492(n-1) + 1 - Lekraj Beedassy, Jul 23 2003

Links

Table of n, a(n) for n=1..43.

Example

531 is in the sequence because it is the first term of the ten consecutive composites:531 = 3^2*59; 532 = 2^2*7*19; 533 = 13*41; 534 = 2*3*89; 535 = 5*107; 536 = 2^3*67; 537 = 3*179; 538 = 2*269; 539 = 7^2*11; 540 = 2^2*3^3*5.

Prog

(PARI) isok(n) = {if ((n % 10) != 1, return (0)); for (k = 0, 9, if (isprime(n + k), return (0)); ); return (1); } \\ Michel Marcus, Jul 27 2013

Crossrefs

Cf. A007530, A076150.

Sequence in context: A347887 A353081 A259768 * A157956 A202771 A183350

Adjacent sequences: A076189 A076190 A076191 * A076193 A076194 A076195

Keyword

nonn

Author

Lekraj Beedassy, Oct 31 2002

Extensions

Edited, corrected and extended by Robert G. Wilson v, Nov 04 2002

Status

approved