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 1-10 of 10 results.

A061152 Expansion of Product_{n>=1} (1+x^n)^prime(n).

Original entry on oeis.org

1, 2, 4, 11, 23, 51, 107, 216, 430, 839, 1614, 3046, 5684, 10465, 19046, 34321, 61225, 108245, 189779, 330093, 569916, 977139, 1664304, 2817039, 4740000, 7930740, 13198108, 21851556, 36001483, 59035979, 96373100, 156644241, 253550911
Offset: 0

Views

Author

Vladeta Jovovic, Apr 16 2001

Keywords

Crossrefs

Formula

a(n) = (1/n) * Sum_{k=1..n} a(n-k)*b(k), k>0, a(0)=1, b(k)=Sum_{d|k} (-1)^(k/d+1)*d*prime(d).

A007441 1 + Sum_{n>=1} a_n x^n = Product_{n>=1} (1-x^n)^prime(n).

Original entry on oeis.org

1, -2, -2, 1, 3, 7, 5, 6, -10, -27, -50, -42, -30, 41, 148, 241, 345, 303, 167, -275, -858, -1685, -2342, -2813, -2316, -536, 2914, 8228, 14531, 20955, 24370, 22393, 10265, -13839, -53386, -104364, -161593, -209463, -228141, -188750, -62023, 177547, 541310, 1009998, 1527972, 1976120, 2189974
Offset: 0

Views

Author

Keywords

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Formula

a(n) = (1/n)*Sum_{k=1..n} a(n-k)*b(k), k>0, a(0)=1, b(k)=-Sum_{d|k} d*prime(d), cf. A061150.

Extensions

Better description from Vladeta Jovovic, Apr 16 2001

A061150 a(n) = Sum_{d|n} d*prime(d).

Original entry on oeis.org

2, 8, 17, 36, 57, 101, 121, 188, 224, 353, 343, 573, 535, 729, 777, 1036, 1005, 1406, 1275, 1801, 1669, 2087, 1911, 2861, 2482, 3167, 3005, 3753, 3163, 4541, 3939, 5228, 4879, 5737, 5391, 7314, 5811, 7475, 7063, 8873, 7341, 9957, 8215, 10607, 9849
Offset: 1

Views

Author

Vladeta Jovovic, Apr 16 2001

Keywords

Examples

			a(4)=36 because the divisors of 4 are 1,2,4 and 1*p(1) + 2*p(2) + 4*p(4) = 1*2 + 2*3 + 4*7 = 36.
		

Crossrefs

Programs

  • Maple
    with(numtheory): a:=proc(n) local div: div:=divisors(n): sum(div[j]*ithprime(div[j]),j=1..tau(n)) end: seq(a(n),n=1..55); # Emeric Deutsch, Jan 20 2007
  • PARI
    a(n) = sumdiv(n, d, d*prime(d)); \\ Michel Marcus, Jun 24 2018

Formula

Equals M * V, where M = A127093 as an infinite lower triangular matrix and V = A000040, the sequence of primes as a vector. E.g., a(4) = 36 = 1*2 + 2*3 + 4*7, where (1, 2, 0, 4) = row 4 of A127093 and 2, 3 and 7 are p(1), p(2), p(4). - Gary W. Adamson, Jan 11 2007
L.g.f.: log(Product_{k>=1} 1/(1 - x^k)^prime(k)) = Sum_{n>=1} a(n)*x^n/n. - Ilya Gutkovskiy, May 10 2017

Extensions

Edited by N. J. A. Sloane, May 04 2007

A061151 1 + Sum_{n>=1} a_n x^n = 1/Product_{n>=1} (1+x^n)^prime(n).

Original entry on oeis.org

1, -2, 0, -3, 5, -3, 14, -4, 25, -32, 16, -88, 18, -155, 108, -153, 393, -88, 855, -160, 1255, -974, 1122, -3172, 370, -6794, 383, -10017, 5004, -9460, 19380, -2635, 45790, 5008, 76263, -7353, 87597, -77967, 48886, -244397, -45016, -500016, -115318, -734277, 56213, -710603, 810177, -161662, 2432173, 910752, 4767086
Offset: 0

Views

Author

Vladeta Jovovic, Apr 16 2001

Keywords

Crossrefs

Formula

a(n) = (1/n) * Sum_{k=1..n} a(n-k)*b(k), k>0, a(0)=1, b(k)=Sum_{d|k} (-1)^(k/d)*d*prime(d).

A353065 Euler transform of odd primes.

Original entry on oeis.org

1, 3, 11, 32, 92, 239, 608, 1465, 3450, 7858, 17525, 38165, 81653, 171497, 354785, 723084, 1454642, 2889854, 5676607, 11031046, 21224439, 40453596, 76428636, 143192339, 266172016, 491072611, 899583306, 1636775949, 2958900040, 5316004485, 9494514599
Offset: 0

Views

Author

Ilya Gutkovskiy, Apr 21 2022

Keywords

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember; `if`(n=0, 1, add(a(n-j)*add(
          d*ithprime(d+1), d=numtheory[divisors](j)), j=1..n)/n)
        end:
    seq(a(n), n=0..30);  # Alois P. Heinz, Apr 21 2022
  • Mathematica
    nmax = 30; CoefficientList[Series[Product[1/(1 - x^k)^Prime[k + 1], {k, 1, nmax}], {x, 0, nmax}], x]
    a[0] = 1; a[n_] := a[n] = (1/n) Sum[Sum[d Prime[d + 1], {d, Divisors[k]}] a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 30}]

Formula

G.f.: Product_{k>=1} 1 / (1 - x^k)^prime(k+1).

A380497 Euler transform of primorial numbers.

Original entry on oeis.org

1, 2, 9, 46, 314, 3072, 37641, 603510, 11148030, 249327430, 7040987792, 216220333314, 7895699690498, 321315600822232, 13770543972819903, 644232544408157820, 33954066516677635554, 1994206929690480710244, 121461036181617491970561, 8111955386813996410196454, 574814471423312085719652432
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 25 2025

Keywords

Crossrefs

Programs

  • Maple
    p:= proc(n) option remember; `if`(n<1, 1, p(n-1)*ithprime(n)) end:
    a:= proc(n) option remember; `if`(n=0, 1, add(a(n-j)*
          add(d*p(d), d=numtheory[divisors](j)), j=1..n)/n)
        end:
    seq(a(n), n=0..20);  # Alois P. Heinz, Jan 25 2025
  • Mathematica
    nmax = 20; CoefficientList[Series[Product[1/(1 - x^k)^Product[Prime[j], {j, k}], {k, 1, nmax}], {x, 0, nmax}], x]
    primorial[n_] := Product[Prime[j], {j, 1, n}]; a[n_] := a[n] = If[n == 0, 1, Sum[Sum[d primorial[d], {d, Divisors[j]}] a[n - j], {j, 1, n}]/n]; Table[a[n], {n, 0, 20}]

Formula

G.f.: Product_{k>=1} 1 / (1 - x^k)^prime(k)#.

A197132 Euler transform of composite numbers.

Original entry on oeis.org

1, 4, 16, 52, 157, 434, 1144, 2862, 6906, 16090, 36449, 80430, 173555, 366802, 761102, 1552569, 3118508, 6174461, 12064383, 23283027, 44419855, 83834278, 156626605, 289839251, 531534746, 966483534, 1743164649, 3119864511, 5543030861, 9779552117, 17139055493
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Maple
    N:= 100: # to use composites <= N
    comps:= remove(isprime,[$4..N]):
    M:= nops(comps):
    G:= mul((1-x^k)^(-comps[k]),k=1..M):
    S:= series(G, x, M+1):
    seq(coeff(S,x,j),j=0..M); # Robert Israel, Jan 30 2018
  • Mathematica
    a[ns_Integer?NonNegative, nf_Integer?NonNegative] := CoefficientList[Series[Product[(1 - x^k)^-FixedPoint[k + PrimePi[#] + 1 &, k], {k, 1, nf}], {x, 0, nf}], x][[ns + 1 ;; nf + 1]]; a[0, 30] (* Robert P. P. McKone, Nov 08 2023 *)

Formula

G.f.: Product_{k>=1} (1-x^k)^-composite(k), where composite(k) = A002808(k) is the k-th composite number.

A301971 a(n) = [x^n] Product_{k>=1} 1/(1 - x^prime(k))^n.

Original entry on oeis.org

1, 0, 2, 3, 10, 30, 77, 252, 682, 2136, 6182, 18766, 56173, 169351, 512990, 1551828, 4720170, 14348289, 43751984, 133502873, 408029510, 1248460587, 3823949824, 11724787763, 35980251181, 110510334780, 339674840715, 1044812449722, 3215861978150, 9904301974294, 30521063942312, 94103983534015
Offset: 0

Views

Author

Ilya Gutkovskiy, Mar 29 2018

Keywords

Comments

Number of partitions of n into prime parts of n kinds.

Crossrefs

Programs

  • Mathematica
    Table[SeriesCoefficient[Product[1/(1 - x^Prime[k])^n, {k, 1, n}], {x, 0, n}], {n, 0, 31}]

A302238 Expansion of Product_{k>=1} ((1 + x^k)/(1 - x^k))^prime(k).

Original entry on oeis.org

1, 4, 14, 46, 136, 382, 1022, 2626, 6530, 15784, 37218, 85842, 194146, 431358, 943038, 2031454, 4316884, 9058662, 18787730, 38542526, 78264298, 157403290, 313712482, 619919350, 1215125262, 2363570168, 4563951858, 8751621598, 16670498062, 31553539214, 59361428202
Offset: 0

Views

Author

Ilya Gutkovskiy, Apr 03 2018

Keywords

Comments

Convolution of the sequences A030009 and A061152.

Crossrefs

Programs

  • Mathematica
    nmax = 30; CoefficientList[Series[Product[((1 + x^k)/(1 - x^k))^Prime[k], {k, 1, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Product_{k>=1} ((1 + x^k)/(1 - x^k))^A000040(k).

A300521 Expansion of Product_{k>=1} (1 - x^prime(k))^prime(k).

Original entry on oeis.org

1, 0, -2, -3, 1, 1, 3, 0, 9, 8, 4, -31, -12, -13, 20, -13, 48, -17, 74, -87, 8, -143, 175, -174, 349, -164, 369, -651, 520, -1004, 1142, -1218, 1652, -1739, 3291, -3933, 3546, -5743, 6170, -8022, 11435, -13230, 17196, -18706, 22958, -31884, 38420, -49802, 58916
Offset: 0

Views

Author

Ilya Gutkovskiy, Mar 08 2018

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 48; CoefficientList[Series[Product[(1 - x^Prime[k])^Prime[k], {k, 1, nmax}], {x, 0, nmax}], x]
    nmax = 48; CoefficientList[Series[Exp[-Sum[DivisorSum[k, Boole[PrimeQ[#]] #^2 &] x^k/k, {k, 1, nmax}]], {x, 0, nmax}], x]

Formula

G.f.: Product_{k>=1} (1 - x^A000040(k))^A000040(k).
G.f.: exp(-Sum_{k>=1} A005063(k)*x^k/k).
Showing 1-10 of 10 results.