A347788
Number of compositions (ordered partitions) of n into at most 2 nonprime parts.
Original entry on oeis.org
1, 1, 1, 0, 1, 2, 1, 2, 2, 3, 5, 2, 4, 4, 5, 5, 8, 4, 8, 6, 8, 7, 11, 6, 12, 9, 13, 9, 14, 10, 16, 12, 14, 13, 19, 13, 22, 14, 17, 17, 22, 16, 24, 18, 22, 19, 25, 18, 28, 21, 28, 21, 28, 22, 32, 25, 30, 25, 33, 26, 38, 28, 31, 29, 38, 29, 42, 30, 34, 33, 42
Offset: 0
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Table[Length@Flatten[Permutations/@IntegerPartitions[n,2,Select[Range@n,!PrimeQ@#&]],1],{n,0,70}] (* Giorgos Kalogeropoulos, Sep 13 2021 *)
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A347788(n) = if(n<2,1,!isprime(n)+sum(k=1,n-1,!(isprime(k)+isprime(n-k)))); \\ Antti Karttunen, Nov 25 2022
A347796
Number of compositions (ordered partitions) of n into at most 3 nonprime parts.
Original entry on oeis.org
1, 1, 1, 1, 1, 2, 4, 2, 5, 6, 8, 11, 8, 13, 17, 17, 23, 25, 27, 33, 38, 37, 50, 48, 58, 63, 73, 70, 89, 82, 107, 102, 122, 112, 148, 136, 164, 161, 185, 173, 223, 196, 241, 231, 268, 254, 304, 273, 332, 318, 364, 348, 403, 364, 444, 415, 477, 448, 525, 479, 567
Offset: 0
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Table[Length@Flatten[Permutations/@IntegerPartitions[n,3,Select[Range@n,!PrimeQ@#&]],1],{n,0,60}] (* Giorgos Kalogeropoulos, Sep 14 2021 *)
A347797
Number of compositions (ordered partitions) of n into at most 4 nonprime parts.
Original entry on oeis.org
1, 1, 1, 1, 2, 2, 4, 6, 5, 10, 14, 15, 24, 21, 35, 45, 48, 65, 77, 89, 114, 129, 148, 184, 205, 239, 285, 310, 361, 410, 459, 522, 593, 636, 740, 804, 911, 969, 1123, 1169, 1350, 1428, 1595, 1687, 1926, 1974, 2270, 2325, 2611, 2726, 3064, 3120, 3547, 3596, 4012, 4155
Offset: 0
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Table[Length@Flatten[Permutations/@IntegerPartitions[n,4,Select[Range@n,!PrimeQ@#&]],1],{n,0,55}] (* Giorgos Kalogeropoulos, Sep 14 2021 *)
A347798
Number of compositions (ordered partitions) of n into at most 5 nonprime parts.
Original entry on oeis.org
1, 1, 1, 1, 2, 3, 4, 6, 10, 10, 19, 25, 29, 46, 50, 75, 103, 110, 162, 194, 240, 309, 368, 444, 565, 654, 795, 960, 1106, 1325, 1560, 1792, 2118, 2436, 2785, 3244, 3691, 4194, 4783, 5419, 6121, 6893, 7780, 8617, 9766, 10790, 12060, 13340, 14851, 16231, 18210
Offset: 0
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Table[Length@Flatten[Permutations/@IntegerPartitions[n,5,Select[Range@n,!PrimeQ@#&]],1],{n,0,50}] (* Giorgos Kalogeropoulos, Sep 14 2021 *)
A347799
Number of compositions (ordered partitions) of n into at most 6 nonprime parts.
Original entry on oeis.org
1, 1, 1, 1, 2, 3, 5, 6, 10, 16, 19, 31, 44, 52, 86, 101, 148, 206, 237, 350, 441, 551, 743, 900, 1151, 1470, 1782, 2216, 2762, 3287, 4072, 4894, 5835, 7052, 8362, 9856, 11758, 13710, 16066, 18791, 21799, 25271, 29192, 33583, 38485, 44178, 50304
Offset: 0
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Table[Length@Flatten[Permutations/@IntegerPartitions[n,6,Select[Range@n,!PrimeQ@#&]],1],{n,0,46}] (* Giorgos Kalogeropoulos, Sep 14 2021 *)
A353429
Number of integer compositions of n with all prime parts and all prime run-lengths.
Original entry on oeis.org
1, 0, 0, 0, 1, 0, 2, 0, 0, 1, 4, 0, 2, 2, 5, 4, 9, 1, 5, 12, 20, 11, 19, 18, 31, 43, 54, 37, 63, 95, 121, 124, 154, 178, 261, 353, 393, 417, 565, 770, 952, 1138, 1326, 1647, 2186, 2824, 3261, 3917, 4941, 6423, 7935, 9719, 11554, 14557, 18536, 23380, 27985
Offset: 0
The a(13) = 2 through a(16) = 9 compositions:
(22333) (77) (555) (3355)
(33322) (2255) (33333) (5533)
(5522) (222333) (22255)
(223322) (333222) (55222)
(2222222) (332233)
(2222233)
(2223322)
(2233222)
(3322222)
A106356 counts compositions by number of adjacent equal parts.
A114901 counts compositions with no runs of length 1, ranked by
A353427.
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b:= proc(n, h) option remember; `if`(n=0, 1, add(`if`(i<>h and isprime(i),
add(`if`(isprime(j), b(n-i*j, i), 0), j=2..n/i), 0), i=2..n/2))
end:
a:= n-> b(n, 0):
seq(a(n), n=0..70); # Alois P. Heinz, May 18 2022
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Table[Length[Select[Join@@Permutations/@IntegerPartitions[n], And@@PrimeQ/@#&&And@@PrimeQ/@Length/@Split[#]&]],{n,0,15}]
A157423
Triangle read by rows, T(n,k) = 0 if (n-k+1) is prime, else 1.
Original entry on oeis.org
1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 0, 1, 0, 0, 1, 1, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 0, 1
Offset: 1
First few rows of the triangle =
1;
0, 1;
0, 0, 1;
1, 0, 0, 1;
0, 1, 0, 0, 1;
1, 0, 1, 0, 0, 1;
0, 1, 0, 1, 0, 0, 1;
1, 0, 1, 0, 1, 0, 0, 1;
1, 1, 0, 1, 0, 1, 0, 0, 1;
1, 1, 1, 0, 1, 0, 1, 0, 0, 1;
0, 1, 1, 1, 0, 1, 0, 1, 0, 0, 1;
1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 0, 1;
0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 0, 1;
1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 0, 1;
...
Example: T(6,4) = 0 since (6 - 4 + 1) = 3, prime.
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Table[If[PrimeQ[n-k+1],0,1],{n,15},{k,n}]//Flatten (* Harvey P. Dale, Jul 19 2016 *)
A276421
Number of palindromic compositions of n into nonprime numbers.
Original entry on oeis.org
1, 1, 1, 1, 2, 1, 3, 1, 5, 3, 7, 4, 11, 6, 16, 9, 25, 14, 38, 21, 59, 34, 89, 50, 137, 77, 208, 117, 319, 180, 486, 273, 744, 420, 1134, 639, 1735, 977, 2648, 1491, 4048, 2281, 6180, 3480, 9444, 5321, 14421, 8122, 22035, 12412, 33655, 18957, 51417, 28966
Offset: 0
a(6) = 3 because we have [6], [1,4,1], and [1,1,1,1,1,1].
a(10) = 7 because we have [10], [1,8,1], [1,1,6,1,1], [1,4,4,1], [4,1,1,4], [1,1,1,4,1,1,1], and [1^{10}].
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F:=sum(z^j,j=1..229)-(sum(z^ithprime(k),k=1..50)): g:=(1+F)/(1-subs(z = z^2, F)): gser:=series(g,z=0,53): seq(coeff(gser,z,n),n=0..50);
# second Maple program:
a:= proc(n) option remember; `if`(isprime(n), 0, 1)+
add(`if`(isprime(j), 0, a(n-2*j)), j=1..n/2)
end:
seq(a(n), n=0..60); # Alois P. Heinz, Sep 03 2016
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a[n_] := a[n] = If[PrimeQ[n], 0, 1] + Sum[If[PrimeQ[j], 0, a[n-2j]], {j, 1, n/2}]; Table[a[n], {n, 0, 60}] (* Jean-François Alcover, Feb 08 2017, after Alois P. Heinz *)
A280544
Expansion of 1/(1 - Sum_{k>=2} (1 - floor(2/d(k)))*x^k), where d(k) is the number of divisors (A000005).
Original entry on oeis.org
1, 0, 0, 0, 1, 0, 1, 0, 2, 1, 3, 0, 5, 2, 8, 3, 13, 5, 22, 10, 34, 18, 58, 31, 94, 57, 153, 99, 254, 172, 417, 302, 685, 523, 1136, 901, 1872, 1557, 3097, 2673, 5133, 4577, 8505, 7843, 14109, 13380, 23440, 22816, 38953, 38855, 64789, 66053, 107871, 112190, 179664, 190369, 299478, 322683, 499501, 546548
Offset: 0
a(10) = 3 because we have [10], [6, 4] and [4, 6].
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nmax = 59; CoefficientList[Series[1/(1 - Sum[(1 - Floor[2/DivisorSigma[0, k]]) x^k, {k, 2, nmax}]), {x, 0, nmax}], x]
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x='x+O('x^60); Vec(1/(1 - sum(k=2, 59, (1 - 2\numdiv(k))*x^k))) \\ Indranil Ghosh, Apr 03 2017
A331917
Number of compositions (ordered partitions) of n into distinct nonprime parts.
Original entry on oeis.org
1, 1, 0, 0, 1, 2, 1, 2, 1, 3, 5, 8, 3, 10, 11, 17, 13, 16, 19, 54, 49, 55, 59, 90, 89, 129, 127, 183, 307, 358, 351, 456, 553, 649, 889, 1015, 1143, 1490, 2219, 1913, 3021, 3394, 4241, 4944, 6663, 6859, 9337, 9522, 12123, 14895, 22425, 18849, 28341, 31468, 41533
Offset: 0
a(10) = 5 because we have [10], [9, 1], [6, 4], [4, 6] and [1, 9].
Comments