A374141 -id:A374141 - cp's OEIS frontend

A374142 a(n) is the smallest number which can be represented as the sum of two distinct nonzero heptagonal numbers in exactly n ways, or -1 if no such number exists.

8, 617, 8726, 255575, 1339801, 2419165, 9402323, 25764500, 35486953, 144568133, 385495261, 735503569, 638279039, 1183071664, 1571634527, 4449717748, 3584182298, 3871587494, 5693954599, 27084640649, 24205505111, 32489035067, 31973745058, 38935021406, 47570693867, 44749048300, 53075499329

Offset: 1

Ilya Gutkovskiy, Jun 28 2024

nonn

			a(2) = 617 = 1 + 616 = 148 + 469.

Michael S. Branicky, Python program for A374141, A374142, and A374143
Eric Weisstein's World of Mathematics, Heptagonal Number

Cf. A000566, A093195, A332989, A342326, A374141, A374143.

Python
```
# see linked program
```

a(8)-a(27) from Michael S. Branicky, Jun 29 2024

A374143 a(n) is the smallest number which can be represented as the sum of two distinct nonzero octagonal numbers in exactly n ways, or -1 if no such number exists.

Original entry on oeis.org

9, 1053, 12641, 68141, 365641, 953181, 2830641, 6232341, 13969041, 23211261, 104733741, 84994021, 175873641, 159851141, 538547641, 602713041, 810204416, 1019740041, 1053265741, 1972957241, 3339356041, 5914492241, 6886737541, 6388758241, 8902368041, 7858982841, 4942246941, 18439299341, 26639916441

Offset: 1

Ilya Gutkovskiy, Jun 28 2024

nonn

			a(2) = 1053 = 8 + 1045 = 408 + 645.

Michael S. Branicky, Table of n, a(n) for n = 1..38
Michael S. Branicky, Python program for A374141, A374142, and A374143
Eric Weisstein's World of Mathematics, Octagonal Number

Cf. A000567, A093195, A332989, A342326, A374141, A374142.

Python
```
# see linked program
```

a(9)-a(29) from Michael S. Branicky, Jun 29 2024

A374144 a(n) is the smallest number which can be represented as the sum of two distinct nonzero n-gonal numbers in exactly n ways, or -1 if no such number exists.

Original entry on oeis.org

81, 1105, 205427, 483031, 9402323, 6232341, 79324200, 768459127, 2265692766, 2413112833, 6737406626, 150437989675, 45319359337, 15140186701

Offset: 3

Ilya Gutkovskiy, Jun 28 2024

			a(3) = 81 = 3 + 78 = 15 + 66 = 36 + 45.

Eric Weisstein's World of Mathematics, Polygonal Number
Michael S. Branicky, Python program for A374144

Cf. A057145, A093195, A332989, A342326, A350405, A374141, A374142, A374143.

Python
```
# see linked program
```

a(9)-a(16) from Michael S. Branicky, Jun 30 2024

A374194 a(n) is the smallest number which can be represented as the sum of two nonzero hexagonal pyramidal numbers in exactly n ways, or -1 if no such number exists.

Original entry on oeis.org

2, 5972, 5170425

Offset: 1

Ilya Gutkovskiy, Jun 30 2024

There are no further positive terms <= 10^15. - Michael S. Branicky, Jun 30 2024

			a(2) = 5972 = 1222 + 4750 = 1925 + 4047.

Eric Weisstein's World of Mathematics, Hexagonal Pyramidal Number

Cf. A002412, A011541, A334013, A374141, A374168, A374193.

cp's OEIS Frontend

A374142 a(n) is the smallest number which can be represented as the sum of two distinct nonzero heptagonal numbers in exactly n ways, or -1 if no such number exists.

Views

Author

Keywords

Examples

Links

Crossrefs

Programs

Python

Extensions

A374143 a(n) is the smallest number which can be represented as the sum of two distinct nonzero octagonal numbers in exactly n ways, or -1 if no such number exists.

Views

Author

Keywords

Examples

Links

Crossrefs

Programs

Python

Extensions

A374144 a(n) is the smallest number which can be represented as the sum of two distinct nonzero n-gonal numbers in exactly n ways, or -1 if no such number exists.

Views

Author

Keywords

Examples

Links

Crossrefs

Programs

Python

Extensions

A374194 a(n) is the smallest number which can be represented as the sum of two nonzero hexagonal pyramidal numbers in exactly n ways, or -1 if no such number exists.

Views

Author

Keywords

Comments

Examples

Links

Crossrefs