A230806 The smallest of 4 consecutive palindromic numbers that are all primes.

1878781, 11782828711, 13828882831, 33694849633, 36331813363, 76093839067, 93121812139, 1018278728101, 1101228221011, 1200528250021, 1237788877321, 1296978796921, 1318608068131, 1449108019441, 1477968697741, 1608678768061, 1713708073171, 1792308032971

Offset: 1

Author

Shyam Sunder Gupta, Oct 30 2013

Keywords

• nonn
• base

Comments

There cannot be 5 consecutive palindromic numbers that are all primes. The central digit of all numbers in the sequence will be 8.

Examples

			1878781 is in the sequence because 1878781, 1879781, 1880881 and 1881881 are consecutive palindromic numbers that are all primes.
		

Links

• Shyam Sunder Gupta, Table of n, a(n) for n = 1..2166

Crossrefs

Cf. A000040, A002113, A002385, A032595.

Programs

Mathematica

a = {}; m = 0; Do[z = n*10^(IntegerLength[n] - 1) + FromDigits@Rest@Reverse@IntegerDigits[n]; If[PrimeQ[z], m = m + 1; If[m == 1, z1 = z]; If[m == 4, AppendTo[a, z1]], m = 0], {n, 1, 1000000000}]