cp's OEIS Frontend

A301516 Numbers n with decimal expansion (d_1, ..., d_k) such that the convex hull of the set of points { (i, d_i), i = 1..k } has positive area.

%I A301516 #16 Aug 03 2022 17:47:46
%S A301516 100,101,102,103,104,105,106,107,108,109,110,112,113,114,115,116,117,
%T A301516 118,119,120,121,122,124,125,126,127,128,129,130,131,132,133,134,136,
%U A301516 137,138,139,140,141,142,143,144,145,146,148,149,150,151,152,153,154,155
%N A301516 Numbers n with decimal expansion (d_1, ..., d_k) such that the convex hull of the set of points { (i, d_i), i = 1..k } has positive area.
%C A301516 This sequence is the complement of the straight-line numbers (0..99 alongside A135643).
%C A301516 This sequence first differs from A134999 at n = 857: a(857) = 1001 whereas A134999(857) = 1011.
%H A301516 Michael S. Branicky, <a href="/A301516/b301516.txt">Table of n, a(n) for n = 1..10000</a>
%o A301516 (PARI) is(n, base=10) = my (d=digits(n, base)); for (i=1, #d-2, if (d[i]+d[i+2]-2*d[i+1], return (1))); return (0)
%o A301516 (Python)
%o A301516 def ok(n):
%o A301516     d = list(map(int, str(n)))
%o A301516     return any(d[i]+d[i+2]-2*d[i+1] != 0 for i in range(len(d)-2))
%o A301516 print([k for k in range(1002) if ok(k)]) # _Michael S. Branicky_, Aug 03 2022 after _Rémy Sigrist_
%Y A301516 Cf. A134999, A135643, A302907.
%K A301516 nonn,base
%O A301516 1,1
%A A301516 _Rémy Sigrist_, Dec 16 2018