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.

Showing 1-7 of 7 results.

A382465 Positive integers such that every even digit except the first is immediately preceded by a smaller digit.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 23, 24, 25, 26, 27, 28, 29, 31, 33, 34, 35, 36, 37, 38, 39, 41, 43, 45, 46, 47, 48, 49, 51, 53, 55, 56, 57, 58, 59, 61, 63, 65, 67, 68, 69, 71, 73, 75, 77, 78, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99
Offset: 1

Views

Author

Paolo Xausa, Mar 28 2025

Keywords

Comments

Conjecture: these are the terms of A382462, sorted.

Links

Crossrefs

Cf. A382462, A382464 (complement).
Cf. A377912, A382624, A382938, A383062, A383246, A383248, A383250, A383501.

Programs

  • Mathematica
    A382465Q[k_] := FreeQ[Partition[IntegerDigits[k], 2, 1], {i_, j_?EvenQ} /; i >= j];
Select[Range[100], A382465Q]
  • Python
    def ok(n):
    s = str(n)
    return n and all(d not in "02468" or s[i-1] 0)
print([k for k in range(100) if ok(k)]) # Michael S. Branicky, Apr 30 2025

A383062 Nonnegative integers such that every odd digit except the leftmost is immediately preceded by a smaller digit.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 23, 24, 25, 26, 27, 28, 29, 30, 32, 34, 35, 36, 37, 38, 39, 40, 42, 44, 45, 46, 47, 48, 49, 50, 52, 54, 56, 57, 58, 59, 60, 62, 64, 66, 67, 68, 69, 70, 72, 74, 76, 78, 79, 80, 82, 84, 86, 88, 89, 90
Offset: 1

Views

Author

Paolo Xausa, Apr 18 2025

Keywords

Comments

Conjecture: these are the terms of A383059, sorted.

Links

Crossrefs

Cf. A383059, A383061 (complement).
Cf. A377912, A382465, A382624, A382938, A383246, A383248, A383250, A383501.

Programs

  • Mathematica
    A383062Q[k_] := FreeQ[Partition[IntegerDigits[k], 2, 1], {i_, j_?OddQ} /; i >= j];
Select[Range[0, 100], A383062Q]
  • Python
    def ok(n):
    s = str(n)
    return all(s[i+1] > s[i] for i in range(len(s)-1) if s[i+1] in "13579")
print([k for k in range(91) if ok(k)]) # Michael S. Branicky, Apr 19 2025

A382938 Nonnegative integers such that every odd digit except the leftmost is immediately preceded by a larger digit.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 21, 22, 24, 26, 28, 30, 31, 32, 34, 36, 38, 40, 41, 42, 43, 44, 46, 48, 50, 51, 52, 53, 54, 56, 58, 60, 61, 62, 63, 64, 65, 66, 68, 70, 71, 72, 73, 74, 75, 76, 78, 80, 81, 82, 83, 84, 85, 86, 87, 88, 90, 91, 92, 93, 94, 95
Offset: 1

Views

Author

Paolo Xausa, Apr 14 2025

Keywords

Links

Crossrefs

Cf. A382937 (complement).
Cf. A377912, A382465, A382624, A383062, A383246, A383248, A383250, A383501.

Programs

  • Mathematica
    A382938Q[k_] := FreeQ[Partition[IntegerDigits[k], 2, 1], {i_, j_?OddQ} /; i <= j];
Select[Range[0, 100], A382938Q]
  • Python
    def ok(n):
    s = str(n)
    return all(s[i+1] < s[i] for i in range(len(s)-1) if s[i+1] in "13579")
print([k for k in range(96) if ok(k)]) # Michael S. Branicky, Apr 14 2025

A383246 Positive integers without the digit 0 such that every even digit except the rightmost is immediately followed by a smaller digit.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 31, 32, 33, 34, 35, 36, 37, 38, 39, 41, 42, 43, 51, 52, 53, 54, 55, 56, 57, 58, 59, 61, 62, 63, 64, 65, 71, 72, 73, 74, 75, 76, 77, 78, 79, 81, 82, 83, 84, 85, 86, 87, 91, 92, 93, 94, 95, 96, 97, 98, 99
Offset: 1

Views

Author

Paolo Xausa, Apr 20 2025

Keywords

Comments

Conjecture: these are the terms of A342043, sorted.

Links

Crossrefs

Cf. A342043, A383245 (complement).
Cf. A377912, A382465, A382624, A382938, A383062, A383248, A383250, A383501.

Programs

  • Mathematica
    A383246Q[k_] := FreeQ[#, 0] && FreeQ[Partition[#, 2, 1], {i_?EvenQ, j_} /; j >= i] &  [IntegerDigits[k]];
Select[Range[200], A383246Q]
  • Python
    def ok(n):
    s = str(n)
    return "0" not in s and all(d not in "02468" or s[i]Michael S. Branicky, Apr 28 2025

A383248 Nonnegative integers without the digit 9 such that every odd digit except the rightmost is immediately followed by a larger digit.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 26, 27, 28, 34, 35, 36, 37, 38, 40, 41, 42, 43, 44, 45, 46, 47, 48, 56, 57, 58, 60, 61, 62, 63, 64, 65, 66, 67, 68, 78, 80, 81, 82, 83, 84, 85, 86, 87, 88, 120, 121, 122, 123, 124, 125, 126, 127, 128
Offset: 1

Views

Author

Paolo Xausa, Apr 25 2025

Keywords

Comments

Conjecture: these are the terms of A342044, sorted.

Links

Crossrefs

Cf. A342044, A383247 (complement).
Cf. A377912, A382465, A382624, A382938, A383062, A383246, A383250.

Programs

  • Mathematica
    A383248Q[k_] := FreeQ[#, 9] && FreeQ[Partition[#, 2, 1], {i_?OddQ, j_} /; j <= i] & [IntegerDigits[k]];
Select[Range[0, 200], A383248Q]
  • Python
    def ok(n):
    s = str(n)
    return "9" not in s and all(d not in "13579" or s[i]>d for i, d in enumerate(s, 1) if i < len(s))
print([k for k in range(129) if ok(k)]) # Michael S. Branicky, Apr 28 2025

A383249 Positive integers ending with the digit 1, or containing an odd digit d immediately followed by a digit >= d.

Original entry on oeis.org

1, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 31, 33, 34, 35, 36, 37, 38, 39, 41, 51, 55, 56, 57, 58, 59, 61, 71, 77, 78, 79, 81, 91, 99, 101, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135
Offset: 1

Views

Author

Paolo Xausa, Apr 26 2025

Keywords

Comments

Conjecture: these are the numbers missing from A342045.
By way of disjointness and completeness, it is proved that this sequence is the complement of A342045. - Quinn Savitt, Apr 29 2025

Links

Crossrefs

Cf. A342045, A383250 (complement).
Cf. A347298, A382464, A382623, A382937, A383061, A383245, A383247.

Programs

  • Mathematica
    A383249Q[k_] := Last[#] == 1 || MemberQ[Partition[#, 2, 1], {i_?OddQ, j_} /; j >= i] & [IntegerDigits[k]];
Select[Range[200], A383249Q]
  • Python
    def ok(n):
    if n%10 == 1: return True
    s = str(n)
    return any(d in "13579" and s[i]>=d for i, d in enumerate(s, 1) if i < len(s))
print([k for k in range(136) if ok(k)]) # Michael S. Branicky, Apr 28 2025

A383501 Nonnegative integers without the digit 9 such that every odd digit except the leftmost is immediately preceded by a larger digit.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16, 18, 20, 21, 22, 24, 26, 28, 30, 31, 32, 34, 36, 38, 40, 41, 42, 43, 44, 46, 48, 50, 51, 52, 53, 54, 56, 58, 60, 61, 62, 63, 64, 65, 66, 68, 70, 71, 72, 73, 74, 75, 76, 78, 80, 81, 82, 83, 84, 85, 86, 87, 88, 100, 102, 104, 106, 108
Offset: 1

Views

Author

Paolo Xausa, Apr 29 2025

Keywords

Comments

Conjecture: these are the terms of A382935, sorted.

Links

Crossrefs

Cf. A382935, A383500 (complement).
Cf. A377912, A382465, A382624, A382938, A383062, A383246, A383248, A383250.

Programs

  • Mathematica
    A383501Q[k_] := FreeQ[#, 9] && FreeQ[Partition[#, 2, 1], {i_, j_?OddQ} /; i <= j] & [IntegerDigits[k]];
Select[Range[0, 200], A383501Q]
  • Python
    def ok(n):
    s = str(n)
    return "9" not in s and all(d not in "13579" or s[i-1]>d for i, d in enumerate(s) if i > 0)
print([k for k in range(134) if ok(k)]) # Michael S. Branicky, Apr 29 2025
Showing 1-7 of 7 results.

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