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A345984 Partial sums of A011772. 3
1, 4, 6, 13, 17, 20, 26, 41, 49, 53, 63, 71, 83, 90, 95, 126, 142, 150, 168, 183, 189, 200, 222, 237, 261, 273, 299, 306, 334, 349, 379, 442, 453, 469, 483, 491, 527, 546, 558, 573, 613, 633, 675, 707, 716, 739, 785, 817, 865, 889, 906, 945, 997, 1024, 1034, 1082, 1100, 1128, 1186, 1201, 1261 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
How fast is this growing?
LINKS
MATHEMATICA
Accumulate[(Sqrt[1+8#]-1)/2&/@Flatten[With[{r=Accumulate[ Range[ 300]]}, Table[ Select[ r, Divisible[#, n]&, 1], {n, 80}]]]] (* Harvey P. Dale, Sep 19 2021 *)
PROG
(Python 3.8+)
from itertools import combinations, count, islice
from math import prod
from sympy import factorint
from sympy.ntheory.modular import crt
def A345984_gen(): # generator of terms
c = 1
for n in count(4, 2):
yield c
plist = tuple(p**q for p, q in factorint(n).items())
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))))
A345984_list = list(islice(A345984_gen(), 25)) # Chai Wah Wu, Jun 01 2022
CROSSREFS
Sequence in context: A249715 A249440 A063186 * A191198 A191137 A247284
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jul 09 2021
STATUS
approved

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Last modified June 17 18:36 EDT 2024. Contains 373463 sequences. (Running on oeis4.)