A048208 a(n) = T(2n-1,n), array T given by A048201.

1, 6, 17, 37, 63, 98, 139, 186, 240, 298, 359, 431, 505, 589, 683, 779, 892, 1018, 1150, 1288, 1431, 1593, 1762, 1949, 2151, 2366, 2591, 2823, 3061, 3304, 3557, 3820, 4095, 4367, 4645, 4930, 5222, 5530, 5851, 6176, 6517, 6868, 7222, 7582, 7952, 8331, 8710

Offset

1,2

Links

Chai Wah Wu, Table of n, a(n) for n = 1..10000

Formula

a(n) = A004978(2*n) - A004978(n). - Sean A. Irvine, Jun 05 2021

Prog

(Python)
from itertools import count, accumulate, islice
from collections import deque
def A048208_gen(): # generator of terms
    aset, alist, b, blist, c = set(), deque(), 1, [], 0
    for k in count(1):
        if k in aset:
            aset.remove(k)
        else:
            if c&1:
                yield b-blist[c>>1]
            aset |= set(k+d for d in accumulate(alist))
            alist.appendleft(k)
            blist.append(b)
            b += k
            c += 1
A048208_list = list(islice(A048208_gen(), 47)) # Chai Wah Wu, Sep 02 2025

Crossrefs

Cf. A004978, A048201.

Sequence in context: A084990 A024181 A023663 * A212980 A132127 A023621

Adjacent sequences: A048205 A048206 A048207 * A048209 A048210 A048211

Keyword

nonn

Author

Clark Kimberling

Extensions

More terms from Sean A. Irvine, Jun 05 2021

Status

approved