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 1-5 of 5 results.

A038464 Sums of 2 distinct powers of 3.

Original entry on oeis.org

4, 10, 12, 28, 30, 36, 82, 84, 90, 108, 244, 246, 252, 270, 324, 730, 732, 738, 756, 810, 972, 2188, 2190, 2196, 2214, 2268, 2430, 2916, 6562, 6564, 6570, 6588, 6642, 6804, 7290, 8748, 19684, 19686, 19692, 19710, 19764, 19926, 20412, 21870, 26244, 59050, 59052
Offset: 1

Views

Author

Olivier Gérard

Keywords

Links

Crossrefs

Base-3 interpretation of A038444.
Cf. A000244, A038465, A038466, A038467, A038468, A038469.

Programs

  • Mathematica
    Sort[Plus @@@ Subsets[3^Range[0, 10], {2}]] (* Amiram Eldar, Jul 13 2022 *)
  • Python
    from math import isqrt
def A038464(n): return 3**(m:=isqrt(n<<3)+1>>1)+3**(n-1-(m*(m-1)>>1)) # Chai Wah Wu, Apr 05 2025

Extensions

Offset corrected by Amiram Eldar, Jul 13 2022

A038465 Sums of 3 distinct powers of 3.

Original entry on oeis.org

13, 31, 37, 39, 85, 91, 93, 109, 111, 117, 247, 253, 255, 271, 273, 279, 325, 327, 333, 351, 733, 739, 741, 757, 759, 765, 811, 813, 819, 837, 973, 975, 981, 999, 1053, 2191, 2197, 2199, 2215, 2217, 2223, 2269, 2271, 2277, 2295, 2431, 2433, 2439, 2457, 2511, 2917
Offset: 1

Views

Author

Olivier Gérard

Keywords

Links

Crossrefs

Base 3 interpretation of A038445.
Cf. A000244, A038464, A038466, A038467, A038468, A038469.

Programs

  • Mathematica
    Total/@Subsets[3^Range[0,10],{3}]//Union (* Harvey P. Dale, Jul 10 2017 *)
  • Python
    from math import comb, isqrt
from sympy import integer_nthroot
def A038465(n): return 3**((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))+3**((a:=isqrt(s:=n-comb(m-(t^1)+2,3)<<1))+((s<<2)>(a<<2)*(a+1)+1))+3**(m+t+1) # Chai Wah Wu, Apr 04 2025

Extensions

Offset corrected by Amiram Eldar, Jul 13 2022

A038466 Sums of 4 distinct powers of 3.

Original entry on oeis.org

40, 94, 112, 118, 120, 256, 274, 280, 282, 328, 334, 336, 352, 354, 360, 742, 760, 766, 768, 814, 820, 822, 838, 840, 846, 976, 982, 984, 1000, 1002, 1008, 1054, 1056, 1062, 1080, 2200, 2218, 2224, 2226, 2272, 2278, 2280, 2296, 2298, 2304, 2434, 2440, 2442, 2458
Offset: 1

Views

Author

Olivier Gérard

Keywords

Links

Crossrefs

Base 3 interpretation of A038446.
Cf. A000244, A038464, A038465, A038467, A038468, A038469.

Programs

  • Mathematica
    Sort[Plus @@@ Subsets[3^Range[0, 7], {4}]] (* Amiram Eldar, Jul 13 2022 *)
  • Python
    from itertools import islice
def A038466_gen(): # generator of terms
    yield int(bin(n:=15)[2:],3)
    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:],3)
A038466_list = list(islice(A038466_gen(),30)) # Chai Wah Wu, Apr 04 2025

Extensions

Offset corrected by Amiram Eldar, Jul 13 2022

A038468 Sums of 6 distinct powers of 3.

Original entry on oeis.org

364, 850, 1012, 1066, 1084, 1090, 1092, 2308, 2470, 2524, 2542, 2548, 2550, 2956, 3010, 3028, 3034, 3036, 3172, 3190, 3196, 3198, 3244, 3250, 3252, 3268, 3270, 3276, 6682, 6844, 6898, 6916, 6922, 6924, 7330, 7384, 7402, 7408, 7410, 7546, 7564, 7570, 7572, 7618
Offset: 1

Views

Author

Olivier Gérard

Keywords

Links

Crossrefs

Cf. A000244, A038464, A038465, A038466, A038467, A038469.
Base 3 interpretation of A038448.

Programs

  • Mathematica
    Sort[Plus @@@ Subsets[3^Range[0, 8], {6}]] (* Amiram Eldar, Jul 12 2022 *)
  • Python
    from itertools import islice
def A038468_gen(): # generator of terms
    yield int(bin(n:=63)[2:],3)
    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:],3)
A038468_list = list(islice(A038468_gen(),30)) # Chai Wah Wu, Apr 05 2025

Extensions

Offset corrected by Amiram Eldar, Jul 12 2022

A038469 Sums of 7 distinct powers of 3.

Original entry on oeis.org

1093, 2551, 3037, 3199, 3253, 3271, 3277, 3279, 6925, 7411, 7573, 7627, 7645, 7651, 7653, 8869, 9031, 9085, 9103, 9109, 9111, 9517, 9571, 9589, 9595, 9597, 9733, 9751, 9757, 9759, 9805, 9811, 9813, 9829, 9831, 9837, 20047, 20533, 20695, 20749, 20767, 20773, 20775
Offset: 1

Views

Author

Olivier Gérard

Keywords

Links

Crossrefs

Base 3 interpretation of A038449.
Cf. A000244, A038464, A038465, A038466, A038467, A038468.

Programs

  • Mathematica
    Sort[Plus @@@ Subsets[3^Range[0, 8], {7}]] (* Amiram Eldar, Jul 13 2022 *)

Extensions

Offset corrected by Amiram Eldar, Jul 13 2022
Showing 1-5 of 5 results.

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

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