cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A193413 Valley numbers.

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%I A193413 #26 Aug 03 2022 02:35:00
%S A193413 1,2,3,4,5,6,7,8,9,11,22,33,44,55,66,77,88,99,101,111,202,212,222,303,
%T A193413 313,323,333,404,414,424,434,444,505,515,525,535,545,555,606,616,626,
%U A193413 636,646,656,666,707,717,727,737,747,757,767,777,808,818,828,838,848,858,868,878,888,909,919,929,939,949,959,969,979,989,999,1001
%N A193413 Valley numbers.
%C A193413 For n > 10 the structure of digits represents a valley. The first digit is equal to the last digit (1 - 9). The first digits are in nonincreasing order. The last digits are in nondecreasing order. The numbers may have more than one smallest digit. Sequence is infinite.
%C A193413 Superset of crater numbers (A193409) and A193412.
%C A193413 See valley numbers in base 2 (A193414 and A193415).
%e A193413 Illustration using 6543333346:
%e A193413   6 . . . . . . . . 6
%e A193413   . 5 . . . . . . . .
%e A193413   . . 4 . . . . . 4 .
%e A193413   . . . 3 3 3 3 3 . .
%Y A193413 Cf. A110785, A193409, A193412, A193414, A193415.
%Y A193413 Cf. A134970. - _Omar E. Pol_, Aug 05 2011
%K A193413 nonn,base
%O A193413 1,2
%A A193413 _Jaroslav Krizek_, Jul 25 2011
%E A193413 More terms extended by definition by _Jaroslav Krizek_, Jul 27 2011