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.

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A376046 Complement of A325114.

Original entry on oeis.org

7, 14, 17, 21, 27, 28, 35, 37, 42, 47, 49, 56, 57, 63, 67, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 84, 87, 91, 97, 98, 105, 107, 112, 114, 117, 119, 121, 126, 127, 128, 133, 135, 137, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 154, 156, 157, 161, 163, 167
Offset: 1

Views

Author

N. J. A. Sloane, Sep 09 2024

Keywords

Comments

Numbers missing from A325114.
Equivalently, numbers whose decimal expansion has a subsequence which is divisible by 7.
Similar to the "Buzz" sequence A092433, but with a more inclusive definition.
Contains 114.

Links

Crossrefs

Cf. A092433, A325114, A376047.

Programs

  • PARI
    is(n) = { my (d = digits(n)); for (i = 1, #d, if (d[i], for (j = i, #d, my (s = fromdigits(d[i..j])); if (s % 7==0, return (1););););); return (0); } \\ Rémy Sigrist, Nov 16 2024

A328019 Positions of 1 in A328018.

Original entry on oeis.org

1, 7, 35, 119, 387, 1050, 2786, 7160, 17157, 39087, 78453, 167183, 344072, 697116, 1310344, 2455274, 4569557, 7758203, 13461761, 23063807, 39017035, 66702580, 106675941, 172270944, 274763136, 437839603, 693741098, 1044076002, 1596344378, 2414009807, 3653875720
Offset: 1

Views

Author

Rens Reus and David A. Corneth, Oct 01 2019

Keywords

Comments

Does a(n+1)/a(n) tend to 1 as n tends to infinity? - Rémy Sigrist, Nov 11 2019

Examples

			A328018 starts like this: 1, 2, 3, 4, 5, 6, 1, 8, 9, 10, 11, 12, 13, 2, 15, 16, 3, 18, 19, 20, 4, 22, 23, 24, 25, 26, 5, 6, 29, 30, 31, 32, 33, 34, 1, 36, 8, 38, 39, 40.
This has 1's in positions 1, 7 and 35. Therefore, 1, 7 and 35 are in the sequence.

Links

Crossrefs

Cf. A092433, A328018.

Programs

  • Mathematica
    With[{s = Select[Range[10^6], Or[Mod[#, 7] == 0, DigitCount[#, 10, 7] > 0] &]}, Nest[Append[#, s[[#[[-1]] ]] ] &, {1}, 12]] (* Michael De Vlieger, Oct 17 2019 *)
  • PARI
    print1 (w=1", "); k=0; for (n=1, oo, if (n%7==0 || setsearch(Set(digits(n)),7), if (w==k++, print1 (w=n", ")))) \\ Rémy Sigrist, Nov 11 2019
  • PARI
    See Links section.

Formula

a(1) = 1; a(n + 1) = A092433(a(n)) for n > 0.

Extensions

More terms from Rémy Sigrist, Nov 11 2019
Previous Showing 11-12 of 12 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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