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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A087079 Number of lunar partitions of n: number of ways of writing n as a lunar sum of distinct terms, ignoring order.

Original entry on oeis.org

1, 1, 2, 4, 8, 16, 32, 64, 128, 256, 1, 5, 22, 92, 376, 1520, 6112, 24512, 98176, 392960, 2, 22, 200, 1696, 13952, 113152, 911360, 7315456, 58621952, 469368832, 4, 92, 1696, 28928, 477184, 7749632, 124911616, 2005925888, 32153534464, 514926313472, 8
Offset: 0

Views

Author

Marc LeBrun, Oct 09 2003

Keywords

Comments

Without the condition that the numbers are distinct the answers are infinite because 1+1+1+...+1 = 1 in lunar arithmetic - see A087061.

Examples

			a(5) = 16: we can write 5 = 5 + any subset of {4, 3, 2, 1} (16 ways).
a(12) = 22: we can write 12 = 12 + any subset of {11, 10, 2, 1} (16 ways), 12 = 2 + 11 + 10 = 2 + 11 = 2 + 10 and those three with 1 added (6 ways).
		

Crossrefs

Cf. A010036.
The subsequence a(n) where n = 111..11 is A003465. - N. J. A. Sloane, May 21 2011

Programs

  • PARI
    A087079(n) = { my(v, r = 0, i, j, b); v = select(x -> x != 0, digits(n)); for (i = 0, 2^#v - 1, b = Vecrev(binary(i)); b = vector(#v, i, if (i <= #b, b[i], 0)); r += (-1)^vecsum(b) * 2^prod(j = 1, #v, if (b[j] == 1, v[j], v[j] + 1)); ); r/2;} /* Jerome Raulin, Feb 15 2017 */

Formula

For 1 <= a < 10 and 0 <= b < 10, a(10a+b) = 2^(ab+a+b-1)+(2^a-1)(2^b-1)2^(ab-1). - David Wasserman, Apr 14 2005

Extensions

More terms from David Wasserman, Apr 14 2005

A087082 Take bounded lunar divisors of n as defined in A087028, add them using normal addition. See A087121 for their lunar sum.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 55, 56, 56, 55, 53, 50, 46, 41, 35, 28, 64, 65, 66, 65, 63, 60, 56, 51, 45, 38, 72, 73, 74, 75, 73, 70, 66, 61, 55, 48, 79, 80, 81, 82, 83, 80, 76, 71, 65, 58, 85, 86, 87, 88, 89, 90, 86, 81, 75, 68, 90, 91, 92, 93, 94, 95, 96, 91, 85, 78
Offset: 1

Views

Author

Marc LeBrun and N. J. A. Sloane, Oct 19 2003

Keywords

Crossrefs

Extensions

More terms from David Applegate, Nov 07 2003

A087121 Take bounded lunar divisors of n as defined in A087028, add them using lunar addition. See A087082 for their conventional sum.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 59, 59, 59, 59, 59, 59, 59, 59, 59, 59, 69, 69, 69, 69, 69, 69, 69, 69, 69, 69, 79, 79, 79, 79, 79, 79, 79, 79, 79, 79, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 199, 109, 109, 109, 109, 109, 109, 109, 109, 109, 199, 199
Offset: 1

Views

Author

Marc LeBrun and N. J. A. Sloane, Oct 21 2003

Keywords

Comments

Differs from A087052 after 100 terms.

Crossrefs

A088470 Lunar sum of distinct lunar prime divisors of n.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 90, 99, 19, 19, 19, 19, 19, 19, 19, 19, 90, 91, 99, 29, 29, 29, 29, 29, 29, 29, 90, 91, 92, 99, 39, 39, 39, 39, 39, 39, 90, 91, 92, 93, 99, 49, 49, 49, 49, 49, 90, 91, 92, 93, 94, 99, 59, 59, 59, 59, 90, 91, 92, 93, 94, 95, 99, 69, 69, 69
Offset: 1

Views

Author

David Applegate, Nov 11 2003

Keywords

Comments

a(n) = Sum_{p is a lunar divisor of n} p. (Each prime appears at most once in this sum.)

Crossrefs

A088472 Numbers n such that the lunar sum of the distinct lunar prime divisors of n is < n.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 100, 110, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153
Offset: 1

Views

Author

David Applegate, Nov 11 2003

Keywords

Crossrefs

A087027 a(n) = n*m where * is lunar multiplication and m is the ordinary sum n+1.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 110, 111, 112, 113, 114, 115, 116, 117, 118, 120, 210, 221, 222, 223, 224, 225, 226, 227, 228, 230, 310, 321, 332, 333, 334, 335, 336, 337, 338, 340, 410, 421, 432, 443, 444, 445, 446, 447, 448, 450, 510, 521, 532, 543, 554, 555, 556, 557, 558
Offset: 0

Views

Author

Marc LeBrun and N. J. A. Sloane, Oct 19 2003

Keywords

Crossrefs

Cf. A087019.

A088480 Numbers n such that the lunar product of the distinct lunar prime divisors of n is >= n.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69
Offset: 1

Views

Author

David Applegate, Nov 11 2003

Keywords

A181352 In lunar arithmetic, n*(n+1).

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 210, 211, 222, 223, 224, 225, 226, 227, 228, 229, 310, 311, 322, 333, 334, 335, 336, 337, 338, 339, 410, 411, 422, 433, 444, 445, 446, 447, 448, 449, 510, 511, 522, 533, 544, 555, 556, 557, 558, 559, 610, 611, 622, 633, 644, 655, 666, 667, 668, 669, 710, 711, 722, 733
Offset: 0

Views

Author

Keywords

Comments

Not to be confused with A087027, which is the lunar product of n and (the ordinary decimal sum) n+1. Here the 1 is added to n in lunar arithmetic.

Crossrefs

Cf. A087027.

A342955 Array T(n,k), n, k >= 0, read by antidiagonals; the i-th decimal digit of T(n, k) is the smallest of the i-th digits of n and of k.

Original entry on oeis.org

0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 2, 1, 0, 0, 1, 2, 2, 1, 0, 0, 1, 2, 3, 2, 1, 0, 0, 1, 2, 3, 3, 2, 1, 0, 0, 1, 2, 3, 4, 3, 2, 1, 0, 0, 1, 2, 3, 4, 4, 3, 2, 1, 0, 0, 1, 2, 3, 4, 5, 4, 3, 2, 1, 0, 0, 0, 2, 3, 4, 5, 5, 4, 3, 2, 0, 0, 0, 1, 0, 3, 4, 5, 6, 5, 4, 3, 0, 1, 0
Offset: 0

Views

Author

Rémy Sigrist, Apr 03 2021

Keywords

Comments

This sequence has similarities with lunar addition (A087061); here we take the smallest, there the largest digits. It is "lunar multiplication" of corresponding digits.
The bitwise AND operator (A004198) is the binary analog.

Examples

			Array T(n, k) begins:
  n\k|  0  1  2  3  4  5  6  7  8  9  10  11  12  13
  ---+----------------------------------------------
    0|  0  0  0  0  0  0  0  0  0  0   0   0   0   0
    1|  0  1  1  1  1  1  1  1  1  1   0   1   1   1
    2|  0  1  2  2  2  2  2  2  2  2   0   1   2   2
    3|  0  1  2  3  3  3  3  3  3  3   0   1   2   3
    4|  0  1  2  3  4  4  4  4  4  4   0   1   2   3
    5|  0  1  2  3  4  5  5  5  5  5   0   1   2   3
    6|  0  1  2  3  4  5  6  6  6  6   0   1   2   3
    7|  0  1  2  3  4  5  6  7  7  7   0   1   2   3
    8|  0  1  2  3  4  5  6  7  8  8   0   1   2   3
    9|  0  1  2  3  4  5  6  7  8  9   0   1   2   3
   10|  0  0  0  0  0  0  0  0  0  0  10  10  10  10
   11|  0  1  1  1  1  1  1  1  1  1  10  11  11  11
   12|  0  1  2  2  2  2  2  2  2  2  10  11  12  12
   13|  0  1  2  3  3  3  3  3  3  3  10  11  12  13
		

Crossrefs

Cf. A004197 (numerical minimum), A004198 (bitwise minimum), A087061 (digit-wise maximum).

Programs

  • PARI
    T(n,k,base=10) = if (n==0 || k==0, 0, T(n\base,k\base)*base + min(n%base, k%base))

Formula

T(n, k) = T(k, n).
T(m, T(n, k)) = T(T(m, n), k).
T(n, n) = n.
T(n, 0) = 0.
T(n, k) + A087061(n, k) = n + k.

A084666 Lunar primes that are also rational primes.

Original entry on oeis.org

19, 29, 59, 79, 89, 97, 109, 409, 419, 439, 509, 619, 659, 709, 719, 739, 769, 809, 829, 839, 859, 907, 919, 929, 937, 947, 967, 1009, 1019, 1039, 1049, 1069, 1091, 1093, 1097, 1109, 1409, 1609, 1709, 1901, 1907, 2029, 2039, 2069, 2089, 2099, 2129, 2179, 2309
Offset: 1

Views

Author

N. J. A. Sloane, Nov 08 2003

Keywords

Crossrefs

Intersection of A000040 and A087097.
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