cp's OEIS Frontend

A249431 a(n) = A249151(n) - n.

%I A249431 #16 Aug 24 2025 04:25:54
%S A249431 1,0,0,-2,0,-3,0,-6,-6,-5,0,-4,0,-7,-10,-14,0,-15,0,-15,-14,-11,0,-12,
%T A249431 -20,-13,-24,-21,0,-4,0,-30,-22,-17,-28,1,0,-19,-26,1,0,-35,0,-33,-21,
%U A249431 -23,0,-28,-42,-45,-34,-39,0,-51,-44,-20,-38,-29,0,-12,0,-31,1,-62,-52,-55,0,-51,-46,-20,0,-30,0
%N A249431 a(n) = A249151(n) - n.
%C A249431 It seems that A006093 gives the positions of zeros.
%H A249431 Chai Wah Wu, <a href="/A249431/b249431.txt">Table of n, a(n) for n = 0..10000</a> (terms 0..4096 from Antti Karttunen)
%F A249431 a(n) = A249151(n) - n.
%o A249431 (Scheme) (definec (A249431 n) (- (A249151 n) n))
%o A249431 (Python)
%o A249431 from itertools import count
%o A249431 from collections import Counter
%o A249431 from math import comb
%o A249431 from sympy import factorint
%o A249431 def A249431(n):
%o A249431     p = sum((Counter(factorint(comb(n,i))) for i in range(n+1)),start=Counter())
%o A249431     for m in count(1):
%o A249431         f = Counter(factorint(m))
%o A249431         if not f<=p:
%o A249431             return m-1-n
%o A249431         p -= f # _Chai Wah Wu_, Aug 19 2025
%Y A249431 A249433 and A249434 give the positions of negative and nonnegative values, respectively.
%Y A249431 A249430 gives the position where +n appears for the first time, A249432 the positions of records of positive values.
%Y A249431 Cf. A006093, A249151.
%K A249431 sign,changed
%O A249431 0,4
%A A249431 _Antti Karttunen_, Nov 02 2014