A081993 a(n) = sum of numbers formed using the digits of next n numbers.

1, 55, 3330, 6499950, 11199999998880, 714167999999344800, 84083999999999159160, 948587639999999910870960, 23385922559999999977859481600

Offset

1,2

Comments

As with A081991 and A081992, numbers with leading 0's are ignored. - Sean A. Irvine, Nov 20 2025

Links

Table of n, a(n) for n=1..9.

Example

a(3) = 456 + 465 + 546 + 564 + 645 + 654 = 3330.
a(4) = 10789 + 10798 + 10879 + 10897 + 10978 + 10987 + 17089 + 17098 + 17809 + 17890 + 17908 + 17980 + 18079 + 18097 + 18709 + 18790 + 18907 + 18970 + 19078 + 19087 + 19708 + 19780 + 19807 + 19870 + 70189 + 70198 + 70819 + 70891 + 70918 + 70981 + 71089 + 71098 + 71809 + 71890 + 71908 + 71980 + 78019 + 78091 + 78109 + 78190 + 78901 + 78910 + 79018 + 79081 + 79108 + 79180 + 79801 + 79810 + 80179 + 80197 + 80719 + 80791 + 80917 + 80971 + 81079 + 81097 + 81709 + 81790 + 81907 + 81970 + 87019 + 87091 + 87109 + 87190 + 87901 + 87910 + 89017 + 89071 + 89107 + 89170 + 89701 + 89710 + 90178 + 90187 + 90718 + 90781 + 90817 + 90871 + 91078 + 91087 + 91708 + 91780 + 91807 + 91870 + 97018 + 97081 + 97108 + 97180 + 97801 + 97810 + 98017 + 98071 + 98107 + 98170 + 98701 + 98710 = 6499950. - Sean A. Irvine, Nov 20 2025

Prog

(Python)
from sympy.utilities.iterables import multiset_permutations
def a(n):
    digits = sorted("".join(str(i) for i in range((n-1)*n//2+1, (n-1)*n//2+1+n)))
    return sum(int("".join(t)) for t in multiset_permutations(digits) if t[0]!="0")
print([a(n) for n in range(1, 8)]) # Michael S. Branicky, Nov 22 2025

Crossrefs

Cf. A081991, A081992.

Sequence in context: A212736 A221767 A095659 * A060077 A035323 A250833

Adjacent sequences: A081990 A081991 A081992 * A081994 A081995 A081996

Keyword

base,nonn,more

Author

Amarnath Murthy, Apr 05 2003

Extensions

More terms from David Wasserman, Jul 28 2004

a(4)-a(8) corrected by Sean A. Irvine, Nov 20 2025

a(9) from Michael S. Branicky, Nov 24 2025

Status

approved