|
%I #15 Sep 09 2022 08:04:58
%S 17,8,2,13,20,74,90,137,377,3050,986,1669,4181,6530,1493,8434,9704,
%T 22160,10709,5165,16109,154708,58418,31657,52393,401480,176810,101349,
%U 105572,678356,241882,501716,393817,284002,685541,1437353,1751296,3225578,3439258,2479594
%N First occurrence of difference n between two consecutive terms of A000404. a(n) gives the lower term. The upper term is A355238.
%F a(n) = A355238(n) - n.
%o (Python)
%o from itertools import count
%o from sympy import factorint
%o def A355237(n):
%o m = 2
%o for k in count(2):
%o c = False
%o for p in (f:=factorint(k)):
%o if (q:= p & 3)==3 and f[p]&1:
%o break
%o elif q == 1:
%o c = True
%o else:
%o if c or f.get(2,0)&1:
%o if k-m == n:
%o return m
%o m = k # _Chai Wah Wu_, Jul 01 2022
%Y Cf. A000404, A104271, A355238.
%K nonn
%O 1,1
%A _Hugo Pfoertner_, Jun 30 2022
|
