A085924 If k = product (p_i)^(r_i), where p_i are primes in increasing order, then k is a member if concatenation of r_i as decimal numbers forms a palindrome.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 19, 21, 22, 23, 25, 26, 27, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 41, 42, 43, 46, 47, 49, 51, 53, 55, 57, 58, 59, 61, 62, 64, 65, 66, 67, 69, 70, 71, 73, 74, 77, 78, 79, 81, 82, 83, 85, 86, 87, 89, 90, 91, 93, 94, 95

Offset

0,2

Comments

2^10 is the first member of A072774 that is not in this sequence. - David Wasserman, Feb 11 2005

Note: A242414 is a new version of this sequence, which does not have this defect. - Antti Karttunen, May 30 2014

42 is the first member of this sequence that is not in A236510. - N. J. A. Sloane, Jan 27 2014

Links

Table of n, a(n) for n=0..71.

Example

15 is a member as 15 = 3^1*5^1 and 11 is a palindrome.
90 is a member as 90 = 2^1*3^2*5^1 and 121 is a palindrome.
84 is not a member as 84 = 2^2*3^1*7^1, 211 is not a palindrome.
1024 is not a member as 1024 = 2^10, and decimal number string "10" is not a palindrome.

Crossrefs

Differs from a non-base version of this sequence, A242414, in that here terms like 1024 are excluded (please see the Example section), while in latter, A242414(691) = 1024.

Cf. A072774, A103653, A236510.

Sequence in context: A317101 A393924 A304449 * A242414 A360249 A360247

Adjacent sequences: A085921 A085922 A085923 * A085925 A085926 A085927

Keyword

base,less,easy,nonn

Author

Amarnath Murthy and Jason Earls, Jul 12 2003

Extensions

More terms from David Wasserman, Feb 11 2005

Dependence on decimal number system highlighted and a link to the new version, A242414, added by Antti Karttunen, May 30 2014

Status

approved