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 1-9 of 9 results.

A382464 Positive integers that contain an even digit d immediately preceded by a digit >= d.

Original entry on oeis.org

10, 20, 22, 30, 32, 40, 42, 44, 50, 52, 54, 60, 62, 64, 66, 70, 72, 74, 76, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 120, 122, 130, 132, 140, 142, 144, 150, 152, 154, 160, 162, 164, 166, 170, 172, 174, 176, 180
Offset: 1

Views

Author

Paolo Xausa, Mar 28 2025

Keywords

Comments

Conjecture: these are the numbers missing from A382462.

Links

Crossrefs

Cf. A382462, A382465 (complement).
Cf. A347298, A382623, A382937, A383061, A383245, A383247, A383249, A383500.

Programs

  • Mathematica
    A382464Q[k_] := MemberQ[Partition[IntegerDigits[k], 2, 1], {i_, j_?EvenQ} /; i >= j];
Select[Range[200], A382464Q]
  • Python
    def ok(n):
    s = str(n)
    return any(d in "02468" and s[i-1]>=d for i, d in enumerate(s) if i > 0)
print([k for k in range(181) if ok(k)]) # Michael S. Branicky, Apr 30 2025

A382624 Positive integers such that every even digit except the leftmost is immediately preceded by a larger digit.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 20, 21, 23, 25, 27, 29, 30, 31, 32, 33, 35, 37, 39, 40, 41, 42, 43, 45, 47, 49, 50, 51, 52, 53, 54, 55, 57, 59, 60, 61, 62, 63, 64, 65, 67, 69, 70, 71, 72, 73, 74, 75, 76, 77, 79, 80, 81, 82, 83, 84, 85, 86, 87, 89, 90
Offset: 1

Views

Author

Paolo Xausa, Apr 01 2025

Keywords

Comments

Conjecture: these are the terms of A382621, sorted.

Links

Crossrefs

Cf. A377912, A382465, A382621, A382623 (complement).

Programs

  • Mathematica
    A382624Q[k_] := FreeQ[Partition[IntegerDigits[k], 2, 1], {i_, j_?EvenQ} /; i <= j];
Select[Range[100], A382624Q]
  • 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 "02468")
print([k for k in range(1, 91) if ok(k)]) # Michael S. Branicky, Apr 03 2025

A383061 Positive integers that contain an odd digit d immediately preceded by a digit >= d.

Original entry on oeis.org

11, 21, 31, 33, 41, 43, 51, 53, 55, 61, 63, 65, 71, 73, 75, 77, 81, 83, 85, 87, 91, 93, 95, 97, 99, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 121, 131, 133, 141, 143, 151, 153, 155, 161, 163, 165, 171, 173, 175, 177, 181, 183, 185, 187, 191, 193, 195, 197, 199
Offset: 1

Views

Author

Paolo Xausa, Apr 18 2025

Keywords

Comments

Conjecture: these are the numbers missing from A383059.

Links

Crossrefs

Cf. A383059, A383062 (complement).
Cf. A347298, A382464, A382623, A382937, A383245, A383247, A383249, A383500.

Programs

  • Mathematica
    A383061Q[k_] := MemberQ[Partition[IntegerDigits[k], 2, 1], {i_, j_?OddQ} /; i >= j];
Select[Range[200], A383061Q]
  • Python
    def ok(n):
    s = str(n)
    return any(s[i] <= s[i-1] for i in range(1, len(s)) if s[i] in "13579")
print([k for k in range(200) if ok(k)]) # Michael S. Branicky, Apr 19 2025

A382621 Lexicographically earliest sequence of distinct positive integers such that if a digit d in the digit stream (ignoring commas) is even, the previous digit is > d.

Original entry on oeis.org

1, 3, 2, 5, 4, 7, 6, 9, 8, 10, 11, 13, 15, 17, 19, 20, 30, 31, 32, 33, 21, 35, 23, 25, 27, 29, 37, 39, 40, 50, 51, 52, 53, 54, 55, 41, 57, 42, 59, 43, 70, 71, 72, 73, 74, 75, 45, 47, 49, 60, 76, 77, 61, 79, 62, 90, 91, 92, 93, 94, 95, 96, 97, 63, 98, 64, 99, 65, 101, 103
Offset: 1

Views

Author

Paolo Xausa, Apr 01 2025

Keywords

Comments

Could be summarized as "even digit, previous bigger". A variant of A342042.

Links

Crossrefs

Cf. A342042, A382462, A382622, A382623, A382624, A382625.

Programs

  • Mathematica
    A382621list[nmax_] := Module[{a, s, invQ, fu = 2},
  invQ[k_] := invQ[k] = (If[#, s[k] = #]; #) & [MemberQ[Partition[IntegerDigits[k], 2, 1], {i_, j_?EvenQ} /; i <= j]];
  s[_] := False; s[1] = True;
  NestList[(a = fu; While[s[a] || invQ[a] || invQ[# + First[IntegerDigits[a]]], a++] & [Max[Mod[#, 10], 1]*10]; While[s[fu], fu++]; s[a] = True; a) &, 1, nmax - 1]];
A382621list[100]
  • Python
    from itertools import count, islice
def cond(s):
    return all(s[i+1] < s[i] for i in range(len(s)-1) if s[i+1] in "02468")
def agen(): # generator of terms
    an, seen, s, m = 1, {1}, "1", 2
    while True:
        yield an
        an = next(k for k in count(m) if k not in seen and cond(s[-1]+str(k)))
        seen.add(an); s += str(an)
        while m in seen or not cond(str(m)): m += 1
print(list(islice(agen(), 70))) # Michael S. Branicky, Apr 03 2025

A382937 Positive integers that contain an odd digit d immediately preceded by a digit <= d.

Original entry on oeis.org

11, 13, 15, 17, 19, 23, 25, 27, 29, 33, 35, 37, 39, 45, 47, 49, 55, 57, 59, 67, 69, 77, 79, 89, 99, 101, 103, 105, 107, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 123, 125, 127, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 145, 147, 149, 150
Offset: 1

Views

Author

Paolo Xausa, Apr 14 2025

Keywords

Links

Crossrefs

Cf. A382938 (complement).
Cf. A347298, A382464, A382623, A383061, A383245, A383247, A383249, A383500.

Programs

  • Mathematica
    A382937Q[k_] := MemberQ[Partition[IntegerDigits[k], 2, 1], {i_, j_?OddQ} /; i <= j];
Select[Range[200], A382937Q]
  • Python
    def ok(n):
    s = str(n)
    return any(s[i+1] >= s[i] for i in range(len(s)-1) if s[i+1] in "13579")
print([k for k in range(1, 151) if ok(k)]) # Michael S. Branicky, Apr 14 2025

A383245 Nonnegative integers that contain the digit 0, or an even digit d immediately followed by a digit >= d.

Original entry on oeis.org

0, 10, 20, 22, 23, 24, 25, 26, 27, 28, 29, 30, 40, 44, 45, 46, 47, 48, 49, 50, 60, 66, 67, 68, 69, 70, 80, 88, 89, 90, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 120, 122, 123, 124, 125, 126, 127, 128, 129, 130, 140, 144, 145, 146, 147, 148, 149, 150, 160, 166
Offset: 1

Views

Author

Paolo Xausa, Apr 20 2025

Keywords

Comments

Conjecture: these are the numbers missing from A342043.

Links

Crossrefs

Cf. A342043, A383246 (complement).
Cf. A347298, A382464, A382623, A382937, A383061, A383247, A383249, A383500.

Programs

  • Mathematica
    A383245Q[k_] := MemberQ[#, 0] || MemberQ[Partition[#, 2, 1], {i_?EvenQ, j_} /; j >= i] & [IntegerDigits[k]];
Select[Range[0, 200], A383245Q]
  • Python
    def ok(n):
    if n%10 == 0: return True
    s = str(n)
    return any(d in "02468" and s[i]>=d for i, d in enumerate(s, 1) if i < len(s))
print([k for k in range(167) if ok(k)]) # Michael S. Branicky, Apr 28 2025

A383247 Positive integers that contain the digit 9, or an odd digit d immediately followed by a digit <= d.

Original entry on oeis.org

9, 10, 11, 19, 29, 30, 31, 32, 33, 39, 49, 50, 51, 52, 53, 54, 55, 59, 69, 70, 71, 72, 73, 74, 75, 76, 77, 79, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 129, 130, 131, 132, 133
Offset: 1

Views

Author

Paolo Xausa, Apr 25 2025

Keywords

Comments

Conjecture: these are the numbers missing from A342044.

Links

Crossrefs

Cf. A342044, A383248 (complement).
Cf. A347298, A382464, A382623, A382937, A383061, A383245, A383249.

Programs

  • Mathematica
    A383247Q[k_] := MemberQ[#, 9] || MemberQ[Partition[#, 2, 1], {i_?OddQ, j_} /; j <= i] & [IntegerDigits[k]];
Select[Range[200], A383247Q]
  • Python
    def ok(n):
    s = str(n)
    return "9" in s or 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(134) 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

A383500 Positive integers that contain the digit 9, or an odd digit d immediately preceded by a digit <= d.

Original entry on oeis.org

9, 11, 13, 15, 17, 19, 23, 25, 27, 29, 33, 35, 37, 39, 45, 47, 49, 55, 57, 59, 67, 69, 77, 79, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 101, 103, 105, 107, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 123, 125, 127, 129, 130, 131, 132, 133, 134, 135, 136, 137
Offset: 1

Views

Author

Paolo Xausa, Apr 29 2025

Keywords

Comments

Conjecture: these are the numbers missing from A382935.
Theorem: This sequence is the complement of A382935. - Quinn Savitt, May 08 2025

Links

Crossrefs

Cf. A382935, A383501 (complement).
Cf. A347298, A382464, A382623, A382937, A383061, A383245, A383247, A383249.

Programs

  • Mathematica
    A383500Q[k_] := MemberQ[#, 9] || MemberQ[Partition[#, 2, 1], {i_, j_?OddQ} /; i <= j] & [IntegerDigits[k]];
Select[Range[200], A383500Q]
  • Python
    def ok(n):
    s = str(n)
    return "9" in s or any(d in "13579" and 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 1-9 of 9 results.

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