cp's OEIS Frontend

A135602 Right-angled numbers with an internal digit as the vertex.

%I A135602 #15 Aug 03 2022 02:33:55
%S A135602 101,121,212,232,323,343,434,454,545,565,656,676,767,787,878,898,989,
%T A135602 1012,1210,1232,2101,2123,2321,2343,3212,3234,3432,3454,4323,4345,
%U A135602 4543,4565,5434,5456,5654,5676,6545,6567,6765,6787,7656,7678,7876,7898,8767,8789,8987
%N A135602 Right-angled numbers with an internal digit as the vertex.
%C A135602 The structure of digits represents a right angle. The vertex is an internal digit. In the graphic representation the points are connected by imaginary line segments from left to right. This sequence is finite. The final term has 19 digits: 9876543210123456789.
%H A135602 Jens Kruse Andersen, <a href="/A135602/b135602.txt">Table of n, a(n) for n = 1..525</a>
%e A135602 Illustration using the final term of this sequence:
%e A135602   9 . . . . . . . . . . . . . . . . . 9
%e A135602   . 8 . . . . . . . . . . . . . . . 8 .
%e A135602   . . 7 . . . . . . . . . . . . . 7 . .
%e A135602   . . . 6 . . . . . . . . . . . 6 . . .
%e A135602   . . . . 5 . . . . . . . . . 5 . . . .
%e A135602   . . . . . 4 . . . . . . . 4 . . . . .
%e A135602   . . . . . . 3 . . . . . 3 . . . . . .
%e A135602   . . . . . . . 2 . . . 2 . . . . . . .
%e A135602   . . . . . . . . 1 . 1 . . . . . . . .
%e A135602   . . . . . . . . . 0 . . . . . . . . .
%o A135602 (Python)
%o A135602 ups = list(tuple(range(i, j)) for i in range(9) for j in range(i+2, 11))
%o A135602 s = set(L[::-1] + R[1:] for L in ups for R in ups if L[0] == R[0])
%o A135602 s |= set(L[:-1] + R[::-1] for L in ups for R in ups if L[-1] == R[-1])
%o A135602 afull = sorted(int("".join(map(str, t))) for t in s if t[0] != 0)
%o A135602 print(afull[:47]) # _Michael S. Branicky_, Aug 02 2022
%Y A135602 Cf. A134810, A134853, A134941, A134970, A135641, A135642, A135643, A135600, A135601, A135603.
%K A135602 base,fini,full,nonn
%O A135602 1,1
%A A135602 _Omar E. Pol_, Dec 02 2007