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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A229906 Composite numbers whose sum of digits is 19.

Original entry on oeis.org

289, 298, 388, 469, 478, 496, 559, 568, 586, 595, 649, 658, 667, 676, 685, 694, 748, 766, 775, 784, 793, 838, 847, 856, 865, 874, 892, 928, 946, 955, 964, 973, 982, 1099, 1189, 1198, 1288, 1369, 1378, 1387, 1396, 1468, 1477, 1486, 1495, 1558, 1576, 1585, 1594
Offset: 1

Views

Author

Jahangeer Kholdi, Oct 03 2013

Keywords

Links

Crossrefs

Cf. A106759, A166459.

Programs

  • Mathematica
    Select[Range[2000], ! PrimeQ[#] && Total[IntegerDigits[#]] == 19 &] (* T. D. Noe, Oct 04 2013 *)

A229902 a(n) is the smallest m such that 19*m^k+1 is prime for k=1, 2,...,n.

Original entry on oeis.org

10, 10, 10, 2080, 178030, 41697270, 4355942080, 1944616927560
Offset: 1

Views

Author

Jahangeer Kholdi, Oct 04 2013

Keywords

Comments

10 divides all terms.

Crossrefs

Cf. A106759, A166459, A229906, A229626.

Programs

  • Mathematica
    a[1]=10;a[n_]:=a[n]=(For[m=a[n-1]/10,Union[Table[PrimeQ[19(10m)^k+1],{k,n}]]=={True},m++];10m) (* Farideh Firoozbakht Oct 05 2013 *)

Extensions

a(7) from Farideh Firoozbakht Oct 05 2013
a(8) from Tyler Busby, Jan 06 2023

A279771 Numbers n such that the sum of digits of 11n equals 11.

Original entry on oeis.org

19, 28, 37, 46, 55, 64, 73, 82, 190, 280, 370, 460, 550, 640, 730, 820, 919, 928, 937, 946, 955, 964, 973, 982, 991, 1819, 1828, 1837, 1846, 1855, 1864, 1873, 1882, 1891, 1900, 2728, 2737, 2746, 2755, 2764, 2773, 2782, 2791, 2800, 3637, 3646, 3655, 3664
Offset: 1

Views

Author

M. F. Hasler, Dec 23 2016

Keywords

Comments

Inspired by A088404 = A069537/2 through A088410 = A069543/8.

Crossrefs

Cf. A007953 (digital sum), Digital sum of m*n equals m: A088404 = A069537/2, A088405 = A052217/3, A088406 = A063997/4, A088407 = A069540/5, A088408 = A062768/6, A088409 = A063416/7, A088410 = A069543/8.
Cf. A005349 (Niven or Harshad numbers), A245062 (arranged in rows by digit sums).
Numbers with given digital sum: A011557 (1), A052216 (2), A052217 (3), A052218 (4), A052219 (5), A052220 (6), A052221 (7), A052222 (8), A052223 (9), A052224 (10), A166311 (11), A235151 (12), A143164 (13), A235225 (14), A235226 (15), A235227 (16), A166370 (17), A235228 (18), A166459 (19), A235229 (20).
Cf. A279772 (sumdigits(2n) = 4), A279773 (sumdigits(3n) = 6), A279774 (sumdigits(4n) = 8), A279775 (sumdigits(5n) = 10), A279776 (sumdigits(6n) = 12), A279770 (sumdigits(7n) = 14), A279768 (sumdigits(8n) = 16), A279769 (sumdigits(9n) = 18), A279777 (sumdigits(9n) = 27).

Programs

  • Mathematica
    Select[Range@ 3664, Total@IntegerDigits[11 #] == 11 &] (* Michael De Vlieger, Dec 23 2016 *)
  • PARI
    is(n)=sumdigits(11*n)==11
Previous Showing 31-33 of 33 results.

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

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