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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A291350 Numbers k such that k!4 + 2^9 is prime, where k!4 = k!!!! is the quadruple factorial number (A007662).

Original entry on oeis.org

9, 11, 13, 17, 19, 21, 29, 31, 33, 35, 67, 103, 111, 129, 179, 355, 713, 799, 921, 1013, 1389, 1543, 2097, 2287, 3657, 4115, 7031, 10689, 11715, 16401, 16893, 19497, 29737, 35615
Offset: 1

Views

Author

Robert Price, Aug 22 2017

Keywords

Comments

Corresponding primes are: 557, 743, 1097, 10457, 66347, 209357, 151413137, ...
a(35) > 10^5.
Terms > 35 correspond to probable primes.

Examples

			11!4 + 2^9 = 11*7*3*1 + 512 = 743 is prime, so 11 is in the sequence.
		

Crossrefs

Programs

  • Mathematica
    MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
    Select[Range[0, 50000], PrimeQ[MultiFactorial[#, 4] + 2^9] &]

A291351 Numbers k such that k!4 + 2^10 is prime, where k!4 = k!!!! is the quadruple factorial number (A007662).

Original entry on oeis.org

9, 13, 23, 27, 33, 47, 61, 113, 145, 161, 191, 281, 291, 417, 869, 919, 1213, 1297, 1663, 2103, 2297, 2325, 3241, 3895, 4337, 6645, 7911, 8737, 13369, 13555, 19245, 34025, 47779, 48589, 54521, 91355
Offset: 1

Views

Author

Robert Price, Aug 22 2017

Keywords

Comments

Corresponding primes are: 1069, 1609, 1515229, 40884559, 4996617649, ...
a(37) > 10^5.
Terms > 33 correspond to probable primes.

Examples

			13!4 + 2^10 = 13*9*5*1 + 1024 = 1609 is prime, so 13 is in the sequence.
		

Crossrefs

Programs

  • Mathematica
    MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
    Select[Range[0, 50000], PrimeQ[MultiFactorial[#, 4] + 2^10] &]
    Select[Range[10^3],PrimeQ[Times@@Range[#,1,-4]+2^10]&] (* The program generates the first 16 terms of the sequence. *) (* Harvey P. Dale, Feb 08 2025 *)

Extensions

a(36)-a(37) from Robert Price, Sep 25 2019

A291687 Primes of the form k!4+4, where k!4 is the quadruple factorial number (A007662).

Original entry on oeis.org

5, 7, 3469, 9949, 65839, 1514209, 5221129, 40883539, 151412629, 44358635479, 16713607661375629, 36453104912477522894629, 1027438963906784290227656915629, 7419136758370889359733910587728129, 4551830726072842264843919206776501006328129
Offset: 1

Views

Author

Robert Price, Aug 29 2017

Keywords

Crossrefs

Cf. A291122.

Programs

  • Mathematica
    MultiFactorial[n_, k_] := If[n<1, 1, n*MultiFactorial[n-k, k]];
    Select[Table[MultiFactorial[i, 4] + 4, {i, 0, 100}], PrimeQ[#]&]

A045747 Number of prime factors of n!!!! (A007662), with multiplicity.

Original entry on oeis.org

0, 1, 1, 2, 1, 3, 2, 5, 3, 5, 3, 8, 4, 7, 5, 12, 5, 10, 6, 15, 7, 12, 7, 19, 9, 14, 10, 22, 10, 17, 11, 27, 12, 19, 13, 31, 13, 21, 15, 35, 14, 24, 16, 38, 17, 26, 17, 43, 19, 29, 19, 46, 20, 33, 21, 50, 22, 35, 22, 54, 23, 37, 25, 60, 25, 40, 26, 63, 27, 43, 27, 68, 28, 45, 30, 71
Offset: 1

Views

Author

Keywords

Crossrefs

Cf. A001222 (Omega), A007662 (n!!!!).

Programs

  • Mathematica
    NFactorialM[n_Integer, m_Integer] := Block[{k = n, p = Max[1, n]}, While[k > m, k -= m; p *= k]; p]; Table[PrimeOmega[NFactorialM[n, 4]], {n, 100}] (* Wesley Ivan Hurt, May 26 2024 after Robert G. Wilson v *)

Formula

a(n) = A001222(A007662(n)). - Wesley Ivan Hurt, May 26 2024

A108895 Partial sums of quadruple factorial numbers n!!!! (A007662).

Original entry on oeis.org

1, 2, 4, 7, 11, 16, 28, 49, 81, 126, 246, 477, 861, 1446, 3126, 6591, 12735, 22680, 52920, 118755, 241635, 450480, 1115760, 2629965, 5579085, 10800210, 28097490, 68981025, 151556385, 302969010, 821887410, 2089276995, 4731688515
Offset: 0

Views

Author

Jonathan Vos Post, Feb 08 2006

Keywords

Comments

Quadruple factorial numbers n!!!! = n*(n-4)!!!!, 0!!!! = 1!!!! = 1, 2!!!! = 2, 3!!!! = 3. The cumulative sum a(n) is prime for n = 1, 3, 4 and never again, as all values from a(8) = 81 are multiples of 3. The cumulative sum a(n) is semiprime for n = 2, 7 and never again, as all values from a(16) are divisible by both 3 and 5.

Examples

			a(31) = 1 + 1 + 2 + 3 + 4 + 5 + 12 + 21 + 32 + 45 + 120 + 231 + 384 + 585 + 1680 + 3465 + 6144 + 9945 + 30240 + 65835 + 122880 + 208845 + 665280 + 1514205 + 2949120 + 5221125 + 17297280 + 40883535 + 82575360 + 151412625 + 518918400 + 1267389585 = 2089276995 = 3 * 5 * 13 * 337 * 31793.
		

References

  • J. Spanier and K. B. Oldham, An Atlas of Functions, Hemisphere, NY, 1987, p. 23.

Crossrefs

Programs

  • Mathematica
    NFactorialM[n_Integer, m_Integer] := Block[{k = n, p = Max[1, n]}, While[k > m, k -= m; p *= k]; p]; Table[ Sum[ NFactorialM[i, 4], {i, 0, n}], {n, 0, 33}] (* Robert G. Wilson v, Feb 21 2006 *)

Formula

a(n) = Sum_{i=0..n} i!!!!.
a(n) = Sum_{i=0..n} A007662(i).

A328454 Numbers k such that k![4] - 4 is prime, where k![4] = A007662(k) = quadruple factorial.

Original entry on oeis.org

7, 9, 11, 15, 17, 19, 39, 45, 57, 59, 63, 69, 81, 85, 127, 141, 149, 153, 163, 165, 201, 235, 259, 377, 457, 649, 815, 897, 1057, 1433, 1453, 1519, 1759, 3047, 3561, 4151, 7025, 11917, 11971, 15295, 18919, 19449, 20765, 70385, 71293
Offset: 1

Views

Author

Robert Price, Nov 06 2019

Keywords

Comments

a(46) > 10^5.
The first 6 primes associated with this sequence are: 17, 41, 227, 3461, 9941, 65831.

Crossrefs

Programs

  • Mathematica
    MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
    Select[Range[1000], (x = MultiFactorial[#, 4] - 4; x > 0 && PrimeQ[x]) &]

A329112 Numbers k such that k![4] - 8 is prime, where k![4] = A007662(k) = quadruple factorial.

Original entry on oeis.org

7, 9, 11, 13, 15, 19, 21, 23, 29, 35, 37, 55, 57, 77, 85, 139, 243, 251, 433, 667, 671, 895, 2127, 2263, 2293, 2645, 2733, 2845, 3675, 4381, 6453, 6825, 36557, 78531
Offset: 1

Views

Author

Robert Price, Nov 06 2019

Keywords

Comments

a(35) > 10^5.
The first 6 primes associated with this sequence are: 13, 37, 223, 577, 3457, 65827.

Crossrefs

Programs

  • Mathematica
    MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
    Select[Range[1000], (x = MultiFactorial[#, 4] - 8; x > 0 && PrimeQ[x]) &]

A329166 Numbers k such that k![4] - 16 is prime, where k![4] = A007662(k) = quadruple factorial.

Original entry on oeis.org

7, 9, 13, 15, 17, 29, 31, 35, 39, 105, 109, 147, 173, 239, 287, 293, 505, 711, 837, 947, 1015, 1025, 1977, 2917, 4035, 4935, 5935, 7693, 10911, 11367, 12029, 14155, 15221, 17921, 17961, 20521, 23053, 32821, 45147, 45351, 68057, 78315
Offset: 1

Views

Author

Robert Price, Nov 06 2019

Keywords

Comments

a(43) > 10^5.
The first 5 primes associated with this sequence are: 5, 29, 569, 3449, 9929.

Crossrefs

Programs

  • Mathematica
    MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
    Select[Range[1000], (x = MultiFactorial[#, 4] - 16; x > 0 && PrimeQ[x]) &]

A329167 Numbers k such that k![4] - 32 is prime, where k![4] = A007662(k) = quadruple factorial.

Original entry on oeis.org

9, 11, 15, 25, 29, 47, 55, 67, 119, 171, 331, 475, 549, 819, 1151, 1543, 2303, 2749, 3303, 3649, 4065, 4261, 4497, 4873, 9105, 12749, 18677, 20121, 22459, 32489, 35765, 46971, 75843, 79585, 79731
Offset: 1

Views

Author

Robert Price, Nov 06 2019

Keywords

Comments

a(36) > 10^5.
The first 4 primes associated with this sequence are: 13, 199, 3433, 5221093.

Crossrefs

Programs

  • Mathematica
    MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
    Select[Range[1000], (x = MultiFactorial[#, 4] - 32; x > 0 && PrimeQ[x]) &]

A329175 Numbers k such that k![4] - 64 is prime, where k![4] = A007662(k) = quadruple factorial.

Original entry on oeis.org

11, 13, 41, 45, 59, 85, 141, 283, 357, 419, 713, 1149, 1353, 1537, 1669, 2353, 2389, 2543, 5147, 5279, 12801, 30035, 39421, 46969, 61077
Offset: 1

Views

Author

Robert Price, Nov 07 2019

Keywords

Comments

a(26) > 10^5.
The first 3 primes associated with this sequence are: 167, 521, 7579867420061.

Crossrefs

Programs

  • Mathematica
    MultiFactorial[n_, k_] := If[n < 1, 1, n*MultiFactorial[n - k, k]];
    Select[Range[1000], (x = MultiFactorial[#, 4] - 64; x > 0 && PrimeQ[x]) &]
Previous Showing 21-30 of 63 results. Next