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.

A038445 Sums of 3 distinct powers of 10.

Original entry on oeis.org

111, 1011, 1101, 1110, 10011, 10101, 10110, 11001, 11010, 11100, 100011, 100101, 100110, 101001, 101010, 101100, 110001, 110010, 110100, 111000, 1000011, 1000101, 1000110, 1001001, 1001010, 1001100, 1010001, 1010010, 1010100, 1011000, 1100001, 1100010, 1100100
Offset: 1

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Crossrefs

Programs

  • Mathematica
    Sort[Plus @@@ Subsets[10^Range[0, 6], {3}]] (* Amiram Eldar, Jul 12 2022 *)
  • Python
    from math import isqrt, comb
    from sympy import integer_nthroot
    def A038445(n): return 10**((r:=n-1-comb((m:=integer_nthroot(6*n,3)[0])+(t:=(n>comb(m+2,3)))+1,3))-comb((k:=isqrt(b:=r+1<<1))+(b>k*(k+1)),2))+10**((a:=isqrt(s:=n-comb(m-(t^1)+2,3)<<1))+((s<<2)>(a<<2)*(a+1)+1))+10**(m+t+1) # Chai Wah Wu, Mar 10 2025

A038446 Sums of 4 distinct powers of 10.

Original entry on oeis.org

1111, 10111, 11011, 11101, 11110, 100111, 101011, 101101, 101110, 110011, 110101, 110110, 111001, 111010, 111100, 1000111, 1001011, 1001101, 1001110, 1010011, 1010101, 1010110, 1011001, 1011010, 1011100, 1100011, 1100101, 1100110, 1101001, 1101010, 1101100, 1110001
Offset: 1

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Crossrefs

Programs

  • Mathematica
    Total/@Subsets[10^Range[0,6],{4}]//Union (* Harvey P. Dale, Nov 07 2021 *)
  • Python
    from itertools import islice
    def A038446_gen(): # generator of terms
        yield int(bin(n:=15)[2:])
        while True: yield int(bin((n:=n^((a:=-n&n+1)|(a>>1)) if n&1 else ((n&~(b:=n+(a:=n&-n)))>>a.bit_length())^b))[2:])
    A038446_list = list(islice(A038446_gen(),20)) # Chai Wah Wu, Mar 11 2025

Extensions

Offset corrected by Amiram Eldar, Jul 12 2022

A038452 Sums of 10 distinct powers of 10.

Original entry on oeis.org

1111111111, 10111111111, 11011111111, 11101111111, 11110111111, 11111011111, 11111101111, 11111110111, 11111111011, 11111111101, 11111111110, 100111111111, 101011111111, 101101111111, 101110111111, 101111011111, 101111101111, 101111110111, 101111111011, 101111111101
Offset: 1

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Crossrefs

Programs

  • Mathematica
    Take[Union[Total/@Subsets[10^Range[0,15],{10}]],20] (* Harvey P. Dale, Dec 19 2011 *)
  • Python
    from itertools import islice
    def A038452_gen(): # generator of terms
        yield int(bin(n:=1023)[2:])
        while True: yield int(bin((n:=n^((a:=-n&n+1)|(a>>1)) if n&1 else ((n&~(b:=n+(a:=n&-n)))>>a.bit_length())^b))[2:])
    A038452_list = list(islice(A038452_gen(),20)) # Chai Wah Wu, Mar 10 2025

Extensions

Offset changed to 1 by Ivan Neretin, Feb 28 2016

A038448 Sums of 6 distinct powers of 10.

Original entry on oeis.org

111111, 1011111, 1101111, 1110111, 1111011, 1111101, 1111110, 10011111, 10101111, 10110111, 10111011, 10111101, 10111110, 11001111, 11010111, 11011011, 11011101, 11011110, 11100111, 11101011, 11101101, 11101110, 11110011, 11110101, 11110110, 11111001, 11111010
Offset: 1

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Crossrefs

Programs

  • Mathematica
    Sort[Plus @@@ Subsets[10^Range[0, 7], {6}]] (* Amiram Eldar, Jul 12 2022 *)
  • Python
    from itertools import islice
    def A038448_gen(): # generator of terms
        yield int(bin(n:=63)[2:])
        while True: yield int(bin((n:=n^((a:=-n&n+1)|(a>>1)) if n&1 else ((n&~(b:=n+(a:=n&-n)))>>a.bit_length())^b))[2:])
    A038448_list = list(islice(A038448_gen(),20)) # Chai Wah Wu, Mar 11 2025

Extensions

Offset corrected by Amiram Eldar, Jul 12 2022

A038449 Sums of 7 distinct powers of 10.

Original entry on oeis.org

1111111, 10111111, 11011111, 11101111, 11110111, 11111011, 11111101, 11111110, 100111111, 101011111, 101101111, 101110111, 101111011, 101111101, 101111110, 110011111, 110101111, 110110111, 110111011, 110111101, 110111110, 111001111, 111010111, 111011011, 111011101
Offset: 1

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Author

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Crossrefs

Programs

  • Mathematica
    Take[Total/@Subsets[10^Range[0,20],{7}]//Union,20] (* Harvey P. Dale, Feb 25 2018 *)
  • Python
    from itertools import islice
    def A038449_gen(): # generator of terms
        yield int(bin(n:=127)[2:])
        while True: yield int(bin((n:=n^((a:=-n&n+1)|(a>>1)) if n&1 else ((n&~(b:=n+(a:=n&-n)))>>a.bit_length())^b))[2:])
    A038449_list = list(islice(A038449_gen(),20)) # Chai Wah Wu, Mar 11 2025

Extensions

Offset corrected by Amiram Eldar, Jul 12 2022

A038454 Sums of 12 distinct powers of 10.

Original entry on oeis.org

111111111111, 1011111111111, 1101111111111, 1110111111111, 1111011111111, 1111101111111, 1111110111111, 1111111011111, 1111111101111, 1111111110111, 1111111111011, 1111111111101, 1111111111110, 10011111111111, 10101111111111, 10110111111111, 10111011111111, 10111101111111
Offset: 1

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Programs

  • Maple
    N:= 14: # to get all terms of at most N digits
    sort(map(t -> (10^N-1)/9 - add(10^j, j=t),
    combinat:-choose([$0..N-1],N-12))); # Robert Israel, Feb 28 2016
  • Mathematica
    Sort[Plus @@@ Subsets[10^Range[0, 12], {12}]] (* Amiram Eldar, Jul 12 2022 *)
  • Python
    from itertools import islice
    def A038454_gen(): # generator of terms
        yield int(bin(n:=4095)[2:])
        while True: yield int(bin((n:=n^((a:=-n&n+1)|(a>>1)) if n&1 else ((n&~(b:=n+(a:=n&-n)))>>a.bit_length())^b))[2:])
    A038454_list = list(islice(A038454_gen(),20)) # Chai Wah Wu, Mar 11 2025

Formula

a(binomial(N,12)+k) = 10^N + A038453(k) for 1 <= k <= binomial(N,11). - Robert Israel, Feb 28 2016

Extensions

Offset changed to 1 by Ivan Neretin, Feb 28 2016

A038450 Sums of 8 distinct powers of 10.

Original entry on oeis.org

11111111, 101111111, 110111111, 111011111, 111101111, 111110111, 111111011, 111111101, 111111110, 1001111111, 1010111111, 1011011111, 1011101111, 1011110111, 1011111011, 1011111101, 1011111110, 1100111111, 1101011111, 1101101111, 1101110111, 1101111011, 1101111101
Offset: 1

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Programs

  • Mathematica
    Sort[FromDigits/@Permutations[{1,1,1,1,1,1,1,1,0,0}]] (* Harvey P. Dale, Apr 29 2013 *)
  • Python
    from itertools import islice
    def A038450_gen(): # generator of terms
        yield int(bin(n:=255)[2:])
        while True: yield int(bin((n:=n^((a:=-n&n+1)|(a>>1)) if n&1 else ((n&~(b:=n+(a:=n&-n)))>>a.bit_length())^b))[2:])
    A038450_list = list(islice(A038450_gen(),20)) # Chai Wah Wu, Mar 11 2025

Extensions

Offset corrected by Amiram Eldar, Jul 12 2022

A038451 Sums of 9 distinct powers of 10.

Original entry on oeis.org

111111111, 1011111111, 1101111111, 1110111111, 1111011111, 1111101111, 1111110111, 1111111011, 1111111101, 1111111110, 10011111111, 10101111111, 10110111111, 10111011111, 10111101111, 10111110111, 10111111011
Offset: 1

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Author

Keywords

Crossrefs

Programs

  • Mathematica
    Sort[Plus @@@ Subsets[10^Range[0, 10], {9}]] (* Amiram Eldar, Jul 12 2022 *)
  • Python
    from itertools import islice
    def A038451_gen(): # generator of terms
        yield int(bin(n:=511)[2:])
        while True: yield int(bin((n:=n^((a:=-n&n+1)|(a>>1)) if n&1 else ((n&~(b:=n+(a:=n&-n)))>>a.bit_length())^b))[2:])
    A038451_list = list(islice(A038451_gen(),20)) # Chai Wah Wu, Mar 11 2025

Extensions

Offset corrected by Amiram Eldar, Jul 12 2022

A038462 Sums of 11 distinct powers of 2.

Original entry on oeis.org

2047, 3071, 3583, 3839, 3967, 4031, 4063, 4079, 4087, 4091, 4093, 4094, 5119, 5631, 5887, 6015, 6079, 6111, 6127, 6135, 6139, 6141, 6142, 6655, 6911, 7039, 7103, 7135, 7151, 7159, 7163, 7165, 7166, 7423, 7551, 7615, 7647, 7663, 7671
Offset: 1

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Crossrefs

Base 2 interpretation of A038453.
Cf. A000079, A018900, A014311, A014312, A014313, A023688, A023689, A023690, A023691, A038461 (Hamming weight = 1, 2, ..., 10).

Programs

  • Mathematica
    Select[Range[8000], DigitCount[#, 2, 1] == 11 &] (* Amiram Eldar, Feb 14 2022 *)
  • Python
    from itertools import islice
    def A038462_gen(): # generator of terms
        yield (n:=2047)
        while True: yield (n:=n^((a:=-n&n+1)|(a>>1)) if n&1 else ((n&~(b:=n+(a:=n&-n)))>>a.bit_length())^b)
    A038462_list = list(islice(A038462_gen(),20)) # Chai Wah Wu, Mar 10 2025

Formula

Sum_{n>=1} 1/a(n) = 1.386300330514503033229968047555778179200262625510401687087371496738972082061... (calculated using Baillie's irwinSums.m, see Links). - Amiram Eldar, Feb 14 2022

Extensions

Offset changed to 1 by Ivan Neretin, Feb 28 2016
Showing 1-9 of 9 results.