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.

Previous Showing 31-36 of 36 results.

A375460 Lexicographically earliest sequence of distinct nonnegative terms arranged in successive chunks whose digitsum = 10.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 10, 11, 20, 6, 12, 100, 7, 21, 8, 101, 9, 1000, 13, 14, 10000, 15, 22, 16, 30, 17, 110, 18, 100000, 19, 23, 31, 1000000, 24, 40, 25, 102, 26, 200, 27, 10000000, 28, 32, 41, 33, 103, 34, 111, 35, 1001, 36, 100000000, 37, 42, 112, 43, 120, 44, 1010, 45, 1000000000
Offset: 1

Views

Author

Eric Angelini, Aug 15 2024

Keywords

Comments

The first integer that will never appear in the sequence is 29, as its digitsum exceeds 10.
From Michael S. Branicky, Aug 16 2024: (Start)
Infinite since A052224 is infinite (as are all sequences with digital sum 1..10).
a(6492) has 1001 digits. (End)

Examples

			The first chunk of integers with digitsum 10 is (0,1,2,3,4);
the next one is (5,10,11,20),
the next one is (6,12,100),
the next one is (7,21),
the next one is (8,101),
the next one is (9,1000),
the next one is (13,14,10000), etc.
The concatenation of the above chunks produce the sequence.
		

Crossrefs

Numbers with digital sum 1..10: A011557 (1), A052216 (2), A052217 (3), A052218 (4), A052219 (5), A052220 (6), A052221 (7), A052222 (8), A052223 (9), A052224 (10).

Programs

  • Python
    from itertools import islice
    def bgen(ds): # generator of terms with digital sum ds
        def A051885(n): return ((n%9)+1)*10**(n//9)-1 # due to Chai Wah Wu
        def A228915(n): # due to M. F. Hasler
            p = r = 0
            while True:
                d = n % 10
                if d < 9 and r: return (n+1)*10**p + A051885(r-1)
                n //= 10; r += d; p += 1
        k = A051885(ds)
        while True: yield k; k = A228915(k)
    def agen(): # generator of terms
        an, ds_block = 0, 0
        dsg = [None] + [bgen(i) for i in range(1, 11)]
        dsi = [None] + [(next(dsg[i]), i) for i in range(1, 11)]
        while True:
            yield an
            an, ds_an = min(dsi[j] for j in range(1, 11-ds_block))
            ds_block = (ds_block + ds_an)%10
            dsi[ds_an] = (next(dsg[ds_an]), ds_an)
    print(list(islice(agen(), 61))) # Michael S. Branicky, Aug 16 2024

Extensions

a(46) and beyond from Michael S. Branicky, Aug 16 2024.

A121476 Palindromes with digit sum 9.

Original entry on oeis.org

9, 171, 252, 333, 414, 10701, 11511, 12321, 13131, 20502, 21312, 22122, 30303, 31113, 40104, 1007001, 1015101, 1023201, 1031301, 1105011, 1113111, 1121211, 1203021, 1211121, 1301031, 2005002, 2013102, 2021202, 2103012, 2111112, 2201022, 3003003, 3011103
Offset: 1

Views

Author

Lekraj Beedassy, Aug 01 2006

Keywords

Crossrefs

Intersection of A002113 and A052223.
Cf. A121477.

Programs

  • Mathematica
    Select[Range[3100000],PalindromeQ[#]&&Total[IntegerDigits[#]]==9&] (* James C. McMahon, Oct 19 2024 *)

Extensions

Missing 1301031 and more terms terms from Sean A. Irvine, Jun 04 2024

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

A333814 Multiples of 12 whose sum of digits is 12.

Original entry on oeis.org

48, 84, 156, 192, 228, 264, 336, 372, 408, 444, 480, 516, 552, 624, 660, 732, 804, 840, 912, 1056, 1092, 1128, 1164, 1236, 1272, 1308, 1344, 1380, 1416, 1452, 1524, 1560, 1632, 1704, 1740, 1812, 1920, 2028, 2064, 2136, 2172, 2208, 2244, 2280, 2316, 2352, 2424
Offset: 1

Views

Author

Bernard Schott, Apr 06 2020

Keywords

Comments

If m is a term, 10*m is also a term.

Examples

			732 = 12 * 61 and 7 + 3 + 2 = 12, hence 732 is a term.
		

Crossrefs

Intersection of A235151 (sum of digits = 12) and A008594 (multiples of 12).
Multiples of k whose sum of digits = k: A011557 (k=1), A069537 (k=2), A052217 (k=3), A063997 (k=4), A069540 (k=5), A062768 (k=6), A063416 (k=7), A069543 (k=8), A052223 (k=9), A333834 (k=10), A283742 (k=11), this sequence (k=12), A283737 (k=13).
Cf. A008594 (multiples of 12), A235151 (sum of digits = 12).
Cf. A057147 (a(n) = n times sum of digits of n).

Programs

  • Mathematica
    Select[12 * Range[200], Plus @@ IntegerDigits[#] == 12 &] (* Amiram Eldar, Apr 06 2020 *)
  • PARI
    is(n)=sumdigits(n)==12 && n%4==0 \\ Charles R Greathouse IV, Apr 07 2020

Formula

a(n) ~ A235151(n). - Charles R Greathouse IV, Apr 07 2020

A333834 Multiples of 10 whose sum of digits is 10.

Original entry on oeis.org

190, 280, 370, 460, 550, 640, 730, 820, 910, 1090, 1180, 1270, 1360, 1450, 1540, 1630, 1720, 1810, 1900, 2080, 2170, 2260, 2350, 2440, 2530, 2620, 2710, 2800, 3070, 3160, 3250, 3340, 3430, 3520, 3610, 3700, 4060, 4150, 4240, 4330, 4420, 4510
Offset: 1

Views

Author

Bernard Schott, Apr 07 2020

Keywords

Comments

If m is a term, 10*m is also a term.
Intersection of A052224 (sum of digits = 10) and A008592 (multiples of 10).

Examples

			2440 = 10 * 244 and 2 + 4 + 4 + 0 = 10, hence 2440 is a term.
		

Crossrefs

Multiples of k whose sum of digits = k: A011557 (k=1), A069537 (k=2), A052217 (k=3), A063997 (k=4), A069540 (k=5), A062768 (k=6), A063416 (k=7), A069543 (k=8), A052223 (k=9), this sequence (k=10), A283742 (k=11), A333814 (k=12), A283737 (k=13).
Subsequence of A218292.
Cf. A008592 (multiples of 10), A052224 (sum of digits = 10).
Cf. A057147 (a(n) = n times sum of digits of n)

Programs

  • Mathematica
    Select[10 * Range[500], Plus @@ IntegerDigits[#] == 10 &] (* Amiram Eldar, Apr 07 2020 *)

Formula

a(n) = 10*A052224(n). - Charles R Greathouse IV, Apr 07 2020

A375824 Triangular numbers whose sum of digits is 9.

Original entry on oeis.org

36, 45, 153, 171, 351, 630, 1035, 1431, 2016, 3240, 3321, 4005, 8001, 10440, 13041, 13203, 16110, 21321, 23220, 25200, 101025, 105111, 114003, 222111, 320400, 321201, 1010331, 1241100, 1313010, 1400301, 2013021, 2031120, 2410110, 4020030, 10006101, 11203011, 20012301, 32004000, 32012001, 33020001
Offset: 1

Views

Author

Robert Israel, Aug 30 2024

Keywords

Comments

Infinite subsequences include 2 * 10^(2*k) + 13 * 10^k + 21, 2 * 10^(2*k) + 31 * 10^k + 120, 32 * 10^(2*k) + 4 * 10^k, and 32 * 10^(2*k) + 12 * 10^k + 1.
Conjecture: the last term not of one of those subsequences is a(53) = 210010000005.

Examples

			a(4) = 153 is a term because 153 = 17 * 18/2 is a triangular number and 1 + 5 + 3 = 9.
		

Crossrefs

Intersection of A000217 and A052223. Contained in A117404 and A076713.

Programs

  • Maple
    F:= proc(d,s) option remember;
    # d-digit numbers with sum of digits s
          local R,i;
          R:= {};
          for i from 0 to min(s,9) do
            R:= R union map(t -> 10*t+i, procname(d-1,s-i))
          od;
          R
    end proc:
    F(1,0):= {}:
    for i from 1 to 9 do F(1,i):= {i} od:
    sort(convert(`union`(seq(select(t -> issqr(1+8*t), F(d,9)),d=1..12)),list));
  • Mathematica
    Select[Range[10000](Range[10000]+1)/2,DigitSum[#]==9 &] (* Stefano Spezia, Sep 01 2024 *)
  • PARI
    select(x->(sumdigits(x)==9), vector(10000, n, n*(n+1)/2)) \\ Michel Marcus, Aug 31 2024
Previous Showing 31-36 of 36 results.