A077543 Smallest n-digit composite palindrome.

4, 22, 111, 1001, 10001, 100001, 1000001, 10000001, 100000001, 1000000001, 10000000001, 100000000001, 1000000000001, 10000000000001, 100000000000001, 1000000000000001, 10000000000000001, 100000000000000001

Offset

1,1

Links

Table of n, a(n) for n=1..18.

Mathematica

a = {4, 22}; Do[k = 10^n; While[d = IntegerDigits[k]; p = FromDigits[ Join[d, Reverse[Drop[d, -1]]]]; PrimeQ[p], k++ ]; a = Append[a, p]; k = 10^n; While[d = IntegerDigits[k]; p = FromDigits[ Join[d, Reverse[d]]]; PrimeQ[p], k++ ]; a = Append[a, p], {n, 1, 8}]; a

Crossrefs

Sequence in context: A159616 A244423 A144047 * A084157 A085939 A192470

Adjacent sequences: A077540 A077541 A077542 * A077544 A077545 A077546

Keyword

base,nonn

Author

Amarnath Murthy, Nov 09 2002

Extensions

Edited and extended by Robert G. Wilson v, Nov 16 2002

Status

approved