cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Previous Showing 11-16 of 16 results.

A213525 Numbers not representable as the sum of three 9-gonal numbers.

Original entry on oeis.org

4, 5, 6, 7, 8, 12, 13, 14, 15, 16, 17, 20, 21, 22, 23, 28, 29, 30, 31, 32, 35, 36, 37, 38, 39, 40, 41, 43, 44, 45, 50, 51, 52, 53, 54, 58, 59, 60, 61, 62, 63, 65, 66, 67, 68, 69, 73, 74, 78, 80, 81, 82, 83, 86, 87, 88, 89, 90, 91, 95, 96, 97, 98, 102, 103
Offset: 1

Views

Author

T. D. Noe, Jul 16 2012

Keywords

Comments

It is conjectured that 5282 positive numbers are not the sum of three 9-gonal numbers.

References

  • R. K. Guy, Unsolved Problems in Number Theory, D3.

Links

Crossrefs

Cf. A001106 (9-gonal numbers).
Cf. A118278, A118279.

Programs

  • Mathematica
    nn = 700; non = Table[n*(7*n - 5)/2, {n, 0, nn}]; t = Table[0, {non[[-1]]}]; Do[n = non[[i]] + non[[j]] + non[[k]]; If[n <= non[[-1]], t[[n]] = 1], {i, nn}, {j, i, nn}, {k, j, nn}]; Flatten[Position[t, 0]]

A214419 Numbers not representable as the sum of three 10-gonal numbers.

Original entry on oeis.org

4, 5, 6, 7, 8, 9, 13, 14, 15, 16, 17, 18, 19, 22, 23, 24, 25, 26, 31, 32, 33, 34, 35, 36, 39, 40, 41, 42, 43, 44, 45, 46, 48, 49, 50, 51, 56, 57, 58, 59, 60, 61, 65, 66, 67, 68, 69, 70, 71, 73, 74, 75, 76, 77, 78, 82, 83, 84, 88, 90, 91, 92, 93, 94, 97, 98
Offset: 1

Views

Author

T. D. Noe, Jul 17 2012

Keywords

Comments

It is conjectured that 7687 positive numbers are not the sum of three 10-gonal numbers.

References

  • R. K. Guy, Unsolved Problems in Number Theory, D3.

Links

Crossrefs

Cf. A001107 (10-gonal numbers).
Cf. A118278, A118279.

Programs

  • Mathematica
    nn = 750; dec = Table[n*(4*n-3), {n, 0, nn}]; t = Table[0, {dec[[-1]]}]; Do[n = dec[[i]] + dec[[j]] + dec[[k]]; If[n <= dec[[-1]], t[[n]] = 1], {i, nn}, {j, i, nn}, {k, j, nn}]; Flatten[Position[t, 0]]

A214420 Numbers not representable as the sum of three 11-gonal numbers.

Original entry on oeis.org

4, 5, 6, 7, 8, 9, 10, 14, 15, 16, 17, 18, 19, 20, 21, 24, 25, 26, 27, 28, 29, 34, 35, 36, 37, 38, 39, 40, 43, 44, 45, 46, 47, 48, 49, 50, 51, 53, 54, 55, 56, 57, 62, 63, 64, 65, 66, 67, 68, 72, 73, 74, 75, 76, 77, 78, 79, 81, 82, 83, 84, 85, 86, 87, 91, 92
Offset: 1

Views

Author

T. D. Noe, Jul 17 2012

Keywords

Comments

It is conjectured that 12453 positive numbers are not the sum of three 11-gonal numbers.

References

  • R. K. Guy, Unsolved Problems in Number Theory, D3.

Links

Crossrefs

Cf. A051682 (11-gonal numbers).
Cf. A118278, A118279.

Programs

  • Mathematica
    nn = 900; hen = Table[n*(9*n-7)/2, {n, 0, nn}]; t = Table[0, {hen[[-1]]}]; Do[n = hen[[i]] + hen[[j]] + hen[[k]]; If[n <= hen[[-1]], t[[n]] = 1], {i, nn}, {j, i, nn}, {k, j, nn}]; Flatten[Position[t, 0]]

A214421 Numbers not representable as the sum of three 12-gonal numbers.

Original entry on oeis.org

4, 5, 6, 7, 8, 9, 10, 11, 15, 16, 17, 18, 19, 20, 21, 22, 23, 26, 27, 28, 29, 30, 31, 32, 37, 38, 39, 40, 41, 42, 43, 44, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 58, 59, 60, 61, 62, 63, 68, 69, 70, 71, 72, 73, 74, 75, 79, 80, 81, 82, 83, 84, 85, 86, 87, 89
Offset: 1

Views

Author

T. D. Noe, Jul 17 2012

Keywords

Comments

There are an infinite number of numbers that are not the sum of three 12-gonal numbers.

References

  • R. K. Guy, Unsolved Problems in Number Theory, D3.

Links

Crossrefs

Cf. A051624 (12-gonal numbers).
Cf. A118278, A118279.

Programs

  • Mathematica
    nn = 100; dod = Table[n*(5n-4), {n, 0, nn}]; t = Table[0, {dod[[-1]]}]; Do[n = dod[[i]] + dod[[j]] + dod[[k]]; If[n <= dod[[-1]], t[[n]] = 1], {i, nn}, {j, i, nn}, {k, j, nn}]; Flatten[Position[t, 0]]

A118281 Conjectured number of numbers that are not the sum of three (2n+1)-gonal numbers; bisection of A118279.

Original entry on oeis.org

0, 210, 1348, 5282, 12453, 24813, 45338, 63702, 109613, 162687, 224244, 303049, 353690, 522262, 651844, 817053
Offset: 1

Views

Author

T. D. Noe, Apr 21 2006

Keywords

Crossrefs

Cf. A118278-A118285.

Extensions

a(11)-a(16) from Donovan Johnson, Apr 17 2010

A118284 Conjectured largest number that is not the sum of three generalized (2n+1)-gonal numbers; bisection of A118282.

Original entry on oeis.org

0, 0, 307, 2027, 18180, 10795, 87740, 75150, 122818, 146970, 585513
Offset: 1

Views

Author

T. D. Noe, Apr 21 2006; revised Apr 23 2006

Keywords

Crossrefs

Cf. A118278-A118285.
Previous Showing 11-16 of 16 results.

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