A345509 -id:A345509 - cp's OEIS frontend

A345499 Numbers that are the sum of nine squares in two or more ways.

24, 27, 30, 32, 33, 35, 36, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95

Offset: 1

David Consiglio, Jr., Jun 20 2021

nonn

			27 is a term because 27 = 1^2 + 1^2 + 1^2 + 1^2 + 1^2 + 1^2 + 1^2 + 2^2 + 4^2 = 1^2 + 1^2 + 1^2 + 2^2 + 2^2 + 2^2 + 2^2 + 2^2 + 2^2.

Sean A. Irvine, Table of n, a(n) for n = 1..1000

Cf. A345489, A345498, A345500, A345509, A345541.

from itertools import combinations_with_replacement as cwr
from collections import defaultdict
keep = defaultdict(lambda: 0)
power_terms = [x**2 for x in range(1, 1000)]
for pos in cwr(power_terms, 9):
    tot = sum(pos)
    keep[tot] += 1
    rets = sorted([k for k, v in keep.items() if v >= 2])
    for x in range(len(rets)):
        print(rets[x])

A345508 Numbers that are the sum of ten squares in one or more ways.

Original entry on oeis.org

10, 13, 16, 18, 19, 21, 22, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81

Offset: 1

David Consiglio, Jr., Jun 19 2021

nonn

			13 is a term because 13 = 1^2 + 1^2 + 1^2 + 1^2 + 1^2 + 1^2 + 1^2 + 1^2 + 1^2 + 2^2.

Sean A. Irvine, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (2,-1).

Cf. A003333, A025429, A345498, A345509.

from itertools import combinations_with_replacement as cwr
from collections import defaultdict
keep = defaultdict(lambda: 0)
power_terms = [x**2 for x in range(1, 1000)]
for pos in cwr(power_terms, 10):
    tot = sum(pos)
    keep[tot] += 1
    rets = sorted([k for k, v in keep.items() if v >= 1])
    for x in range(len(rets)):
        print(rets[x])

def A345508(n): return (10, 13, 16, 18, 19, 21, 22)[n-1] if n<8 else n+16 # Chai Wah Wu, May 09 2024

From Chai Wah Wu, May 09 2024: (Start)
All integers >= 24 are terms. Proof: since 5 can be written as the sum of 5 positive squares and any integer >= 34 can be written as a sum of 5 positive squares (see A025429), any integer >= 39 can be written as a sum of 10 positive squares. Integers from 24 to 38 are terms by inspection.
a(n) = 2*a(n-1) - a(n-2) for n > 9.
G.f.: x*(-x^8 + x^7 - x^6 + x^5 - x^4 - x^3 - 7*x + 10)/(x - 1)^2. (End)

A345550 Numbers that are the sum of ten cubes in two or more ways.

Original entry on oeis.org

73, 80, 99, 134, 136, 141, 148, 155, 160, 162, 167, 169, 174, 176, 183, 186, 188, 190, 192, 193, 195, 197, 199, 202, 204, 206, 209, 211, 212, 213, 214, 216, 218, 221, 223, 225, 228, 230, 232, 235, 239, 240, 244, 246, 247, 249, 251, 253, 254, 258, 260, 262

Offset: 1

David Consiglio, Jr., Jun 20 2021

nonn

			80 is a term because 80 = 1^3 + 1^3 + 1^3 + 1^3 + 1^3 + 1^3 + 1^3 + 1^3 + 2^3 + 3^3 = 2^3 + 2^3 + 2^3 + 2^3 + 2^3 + 2^3 + 2^3 + 2^3 + 2^3 + 2^3.

Sean A. Irvine, Table of n, a(n) for n = 1..10000

Cf. A003333, A345509, A345541, A345551, A345595, A345804.

from itertools import combinations_with_replacement as cwr
from collections import defaultdict
keep = defaultdict(lambda: 0)
power_terms = [x**3 for x in range(1, 1000)]
for pos in cwr(power_terms, 10):
    tot = sum(pos)
    keep[tot] += 1
    rets = sorted([k for k, v in keep.items() if v >= 2])
    for x in range(len(rets)):
        print(rets[x])

A345510 Numbers that are the sum of ten squares in three or more ways.

Original entry on oeis.org

34, 37, 40, 42, 43, 45, 46, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104

Offset: 1

David Consiglio, Jr., Jun 20 2021

nonn

			37 = 1^2 + 1^2 + 1^2 + 1^2 + 1^2 + 1^2 + 1^2 + 1^2 + 2^2 + 5^2
   = 1^2 + 1^2 + 1^2 + 1^2 + 1^2 + 1^2 + 2^2 + 3^2 + 3^2 + 3^2
   = 1^2 + 1^2 + 1^2 + 1^2 + 1^2 + 2^2 + 2^2 + 2^2 + 2^2 + 4^2
   = 1^2 + 2^2 + 2^2 + 2^2 + 2^2 + 2^2 + 2^2 + 2^2 + 2^2 + 2^2
so 37 is a term.

Sean A. Irvine, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (2,-1).

Cf. A345500, A345509, A345551.

from itertools import combinations_with_replacement as cwr
from collections import defaultdict
keep = defaultdict(lambda: 0)
power_terms = [x**2 for x in range(1, 1000)]
for pos in cwr(power_terms, 10):
    tot = sum(pos)
    keep[tot] += 1
    rets = sorted([k for k, v in keep.items() if v >= 3])
    for x in range(len(rets)):
        print(rets[x])

From Chai Wah Wu, May 09 2024: (Start)
All integers >= 48 are terms. Proof: since 29 can be written as the sum of 5 positive squares in 3 ways and any integer >= 34 can be written as a sum of 5 positive squares (see A025429), any integer >= 63 can be written as a sum of 10 positive squares in 3 or more ways. Integers from 48 to 62 are terms by inspection.
a(n) = 2*a(n-1) - a(n-2) for n > 9.
G.f.: x*(-x^8 + x^7 - x^6 + x^5 - x^4 - x^3 - 31*x + 34)/(x - 1)^2. (End)

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A345499 Numbers that are the sum of nine squares in two or more ways.

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A345508 Numbers that are the sum of ten squares in one or more ways.

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A345550 Numbers that are the sum of ten cubes in two or more ways.

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A345510 Numbers that are the sum of ten squares in three or more ways.

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