A345983 - OEIS

%I #21 Dec 04 2022 11:13:34

%S 1,2,4,7,11,13,19,26,34,38,48,51,63,69,74,89,105,113,131,135,141,151,

%T 173,181,205,217,243,250,278,283,313,344,355,371,385,393,429,447,459,

%U 474,514,520,562,573,582,604,650,665,713,737,754,766,818,844,854,861,879,907,965,980,1040,1070

%N Partial sums of A344005.

%H N. J. A. Sloane, <a href="/A345983/b345983.txt">Table of n, a(n) for n = 1..10000</a>

%H N. J. A. Sloane, <a href="/A345983/a345983.txt">Table of n, a(n) for n = 1..100000</a>

%t spm[n_]:=Module[{m=1},While[!Divisible[m(m+1),n],m++];m]; Accumulate[ Array[ spm,100]] (* _Harvey P. Dale_, Dec 04 2022 *)

%o (Python 3.8+)

%o from itertools import combinations, count, islice

%o from math import prod

%o from sympy import factorint

%o from sympy.ntheory.modular import crt

%o def A345983_gen(): # generator of terms

%o     c = 1

%o     for n in count(2):

%o         yield c

%o         plist = tuple(p**q for p, q in factorint(n).items())

%o         c += n-1 if len(plist) == 1 else int(min(min(crt((m, n//m), (0, -1))[0], crt((n//m, m), (0, -1))[0]) for m in (prod(d) for l in range(1, len(plist)//2+1) for d in combinations(plist, l))))

%o A345983_list = list(islice(A345983_gen(),25)) # _Chai Wah Wu_, Jun 01 2022

%Y Cf. A011772, A344005, A345984.

%K nonn

%O 1,2

%A _N. J. A. Sloane_, Jul 09 2021