A070245 Smallest palindromic prime with digit sum = n, or 0 if no such prime exists.

0, 2, 3, 0, 5, 0, 7, 10601, 0, 181, 191, 0, 373, 383, 0, 727, 13931, 0, 757, 929, 0, 787, 797, 0, 17971, 39293, 0, 19891, 19991, 0, 77377, 76667, 0, 78487, 79397, 0, 77977, 78887, 0, 97879, 79997, 0, 1987891, 1988891, 0, 1998991, 3799973, 0, 3899983

Offset

1,2

Comments

a(3k) = 0 for k>1 because if the digital sum is equal to a multiple of 3, then the number is divisible by 3. a(4) = 0 because any palindromic number whose digital sum is 4 is divisible by a number of the form 10^k + 1 for some k.

Links

Chai Wah Wu, Table of n, a(n) for n = 1..150

Mathematica

a = Table[0, {75}]; Do[p = IntegerDigits[Prime[n]]; If[ Reverse[p] == p, q = Plus @ @ p; If[ a[[q]] == 0 && q < 76, a[[q]] = FromDigits[p]]], {n, 1, 10^7}]

Crossrefs

Cf. A002385.

Sequence in context: A071376 A064502 A082809 * A243868 A066398 A138197

Adjacent sequences: A070242 A070243 A070244 * A070246 A070247 A070248

Keyword

base,nonn

Author

Amarnath Murthy, May 05 2002

Extensions

Edited, corrected and extended by Robert G. Wilson v, May 06 2002

Status

approved