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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A269740 Index where A054683(n) appears in A270264.

Original entry on oeis.org

1, 5, 10, 25, 3, 7, 12, 73, 35, 4, 9, 16, 78, 43, 13, 17, 80, 54, 47, 15, 19, 88, 62, 48, 22, 93, 69, 92, 31, 24, 95, 81, 98, 63, 125, 83, 115, 67, 283, 127, 102, 122, 138, 296, 107, 140, 147, 320, 100, 6, 20, 33, 129, 116, 8, 23, 37, 133, 126, 26, 38, 136, 128
Offset: 1

Views

Author

N. J. A. Sloane, Mar 15 2016

Keywords

Comments

Conjectured to be a permutation of the positive numbers excluding 2.
This conjecture is equivalent to Polignac's conjecture. - Chai Wah Wu, Mar 15 2016

Links

Crossrefs

Cf. A054683, A270264.

Extensions

More terms from Chai Wah Wu, Mar 16 2016

A054683 Numbers whose sum of digits is even.

Original entry on oeis.org

0, 2, 4, 6, 8, 11, 13, 15, 17, 19, 20, 22, 24, 26, 28, 31, 33, 35, 37, 39, 40, 42, 44, 46, 48, 51, 53, 55, 57, 59, 60, 62, 64, 66, 68, 71, 73, 75, 77, 79, 80, 82, 84, 86, 88, 91, 93, 95, 97, 99, 101, 103, 105, 107, 109, 110, 112, 114, 116, 118, 121, 123, 125, 127, 129, 130
Offset: 1

Views

Author

Odimar Fabeny, Apr 19 2000

Keywords

Comments

Union of A179082 and A179084; A179081(a(n)) = 0. - Reinhard Zumkeller, Jun 28 2010
Integers with an even number of odd digits. - Bernard Schott, Nov 18 2022

Examples

			0, 2, 4, 6, 8, 11 (2), 13 (4), 15 (6), 17 (8), 19 (10), 20 (2), 22 (4) and so on.

Links

Crossrefs

Cf. A179081, A270264.
Subsequences: A014263, A099814, A179082, A179084.
Similar: A054684 (with an odd number of odd digits), A356929 (with an even number of even digits).

Programs

  • Mathematica
    Select[Range[0,200],EvenQ[Total[IntegerDigits[#]]]&] (* Harvey P. Dale, Jan 04 2015 *)
  • PARI
    is(n)=my(d=digits(n));sum(i=1,#d,d[i])%2==0 \\ Charles R Greathouse IV, Aug 09 2013
  • PARI
    a(n) = n--; m = 10*(n\5); s=sumdigits(m); m + (1-(s-1)%2) + 2*(n%5) \\ David A. Corneth, Jun 05 2016
  • Python
    A054683_list = [i for i in range(10**3) if not sum(int(d) for d in str(i)) % 2] # Chai Wah Wu, Mar 17 2016

Formula

a(n) = 2*n for the first 5 terms; a(n) = 2*n + 1 for the next 5 terms (recurrence).
I.e., for n > 0, a(n + 10) = a(n) + 20. - David A. Corneth, Jun 05 2016

Extensions

More terms from James Sellers, Apr 19 2000
Example corrected by David A. Corneth, Jun 05 2016
Showing 1-2 of 2 results.

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

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