A193407 Mountain numbers (version 2).

1, 2, 3, 4, 5, 6, 7, 8, 9, 121, 131, 141, 151, 161, 171, 181, 191, 232, 242, 252, 262, 272, 282, 292, 343, 353, 363, 373, 383, 393, 454, 464, 474, 484, 494, 565, 575, 585, 595, 676, 686, 696, 787, 797, 898, 1231, 1241, 1251, 1261, 1271, 1281, 1291, 1321

Offset: 1

Author

Jaroslav Krizek, Jul 25 2011

Keywords

• nonn
• base
• fini

Comments

Another version of mountain numbers (A134941).

For n > 9 the structure of digits represents a mountain. The first digit is equal to the last digit (1 - 9). The first digits are in increasing order. The last digits are in decreasing order. The numbers only have one largest digit. This sequence is finite. The final term is 12345678987654321.

Examples

			Illustration using the member of this sequence - number 56789765:
  .  .  .  .  9  .  .  .
  .  .  .  8  .  .  .  .
  .  .  7  .  .  7  .  .
  .  6  .  .  .  .  6  .
  5  .  .  .  .  .  .  5
		

Crossrefs

Supersequence of mountain numbers (A134941) and Giza numbers (A134810). Subsequence of hill numbers (A193408).