A047904
a(n+1) = a(n) + n (if n is odd), a(n+1) = a(n) * n (if n is even).
Original entry on oeis.org
1, 2, 4, 7, 28, 33, 198, 205, 1640, 1649, 16490, 16501, 198012, 198025, 2772350, 2772365, 44357840, 44357857, 798441426, 798441445, 15968828900, 15968828921, 351314236262, 351314236285, 8431541670840, 8431541670865, 219220083442490
Offset: 1
Miklos SZABO (mike(AT)ludens.elte.hu)
-
a047904 n = a047904_list !! (n-1)
a047904_list = 1 : zipWith uncurry
(cycle [(+), (*)]) (zip a047904_list [1..])
-- Reinhard Zumkeller, Nov 13 2013, Mar 24 2013
-
Transpose[NestList[{#[[1]]+1,If[OddQ[#[[1]]],Total[#],Times@@#]}&,{1,1},30]][[2]] (* Harvey P. Dale, Sep 11 2012 *)
-
a=1
for n in range(1,33):
print(a, end=", ")
if n&1:
a += n
else:
a *= n
# Alex Ratushnyak, Feb 24 2013
A047905
a(n+1) = a(n) + n (if n is even), a(n+1) = a(n) * n (if n is odd).
Original entry on oeis.org
1, 1, 3, 9, 13, 65, 71, 497, 505, 4545, 4555, 50105, 50117, 651521, 651535, 9773025, 9773041, 166141697, 166141715, 3156692585, 3156692605, 66290544705, 66290544727, 1524682528721, 1524682528745, 38117063218625, 38117063218651
Offset: 1
Miklos SZABO (mike(AT)ludens.elte.hu)
-
a047905 n = a047905_list !! (n-1)
a047905_list = 1 : zipWith uncurry
(cycle [(*), (+)]) (zip a047905_list [1..])
-- Reinhard Zumkeller, Nov 13 2013, May 31 2011
-
a[0]=1;a[n_]:=a[n]=If[EvenQ[n],a[n-1]+n,a[n-1]n];Join[{1}, Array[a,40]] (* Harvey P. Dale, Apr 24 2011 *)
nxt[{n_,a_}]:={n+1,If[EvenQ[n],a+n,a*n]}; NestList[nxt,{1,1},30][[All,2]] (* Harvey P. Dale, Jul 27 2021 *)
-
a=1
for n in range(1,33):
print(a, end=", ")
if n&1:
a *= n
else:
a += n
# Alex Ratushnyak, Feb 24 2013
A222559
a(0) = 0. If n is odd, a(n) = a(n-1) * n, otherwise a(n) = a(n-1) + n.
Original entry on oeis.org
0, 0, 2, 6, 10, 50, 56, 392, 400, 3600, 3610, 39710, 39722, 516386, 516400, 7746000, 7746016, 131682272, 131682290, 2501963510, 2501963530, 52541234130, 52541234152, 1208448385496, 1208448385520, 30211209638000, 30211209638026, 815702660226702, 815702660226730
Offset: 0
-
last = 0; Table[If[OddQ[n], last = n * last, last = n + last], {n, 0, 40}] (* T. D. Noe, Mar 01 2013 *)
nxt[{n_,a_}]:={n+1,If[EvenQ[n],a(n+1),a+n+1]}; NestList[nxt,{0,0},30][[All,2]] (* Harvey P. Dale, May 14 2019 *)
-
a=0
for n in range(1,33):
print(a, end=',')
if n&1:
a *= n
else:
a += n
A093302
a(n) = (a(n-1)+(2n-1))*(2n) with a(0) = 0.
Original entry on oeis.org
0, 2, 20, 150, 1256, 12650, 151932, 2127230, 34035920, 612646866, 12252937700, 269564629862, 6469551117240, 168208329048890, 4709833213369676, 141294996401091150, 4521439884834917792, 153728956084387206050
Offset: 0
Emrehan Halici (emrehan(AT)halici.com.tr), Apr 24 2004
-
RecurrenceTable[{a[0]==0,a[n]==(a[n-1]+2n-1)2n},a,{n,20}] (* Harvey P. Dale, May 20 2014 *)
-
a(n)=2*floor(exp(1/2)*n!*2^n)-2*n-2
-
x='x+O('x^99); concat(0, Vec(serlaplace((2*x+4*x^2)/(1-2*x)*exp(x)))) \\ Altug Alkan, Aug 01 2018
-
a=vector(99); a[1]=2; for(n=2, #a, a[n] = 2*(a[n-1]+2*n-1)*n); concat(0,a) \\ Altug Alkan, Aug 01 2018
A332657
Alternate adding and multiplying prime numbers: a(2n) = a(2n-1) * prime(2n+1) and a(2n-1) = a(2n) + prime(2n-2) for n >= 1.
Original entry on oeis.org
5, 25, 32, 352, 365, 6205, 6224, 143152, 143181, 4438611, 4438648, 181984568, 181984611, 8553276717, 8553276770, 504643329430, 504643329491, 33811103075897, 33811103075968, 2468210524545664, 2468210524545743, 204861473537296669, 204861473537296758
Offset: 1
a(1) = 2 + 3 = 5;
a(2) = 5 * 5 = 25;
a(3) = 25 + 7 = 32;
...
a(40) = 2714410084880275101596278688487175846.
-
from sympy import primerange
p = list(primerange(1, 200))
def a(n):
out = p[0] + p[1]
for i in range(1, n):
if i % 2:
out *= p[i + 1]
else:
out += p[i + 1]
return out
for n in range(1, 25):
print(a(n), end=", ")
A332659
Alternate multiplying and adding prime numbers: a(2n) = a(2n-1) + prime(2n+1) and a(2n-1) = a(2n) * prime(2n-2) for n >= 1.
Original entry on oeis.org
6, 11, 77, 88, 1144, 1161, 22059, 22082, 640378, 640409, 23695133, 23695174, 1018892482, 1018892529, 54001304037, 54001304096, 3294079549856, 3294079549923, 233879648044533, 233879648044606, 18476492195523874, 18476492195523957, 1644407805401632173
Offset: 1
a(1) = 2 * 3 = 6;
a(2) = 6 + 5 = 11;
a(3) = 11 * 7 = 77.
A332660
Alternate adding and multiplying Fibonacci numbers: a(0) = F(0) + F(1), for n >= 0, a(2n+1) = a(2n) * F(2n+2), a(2n+2) = a(2n+1) + F(2n+3).
Original entry on oeis.org
1, 1, 3, 9, 14, 112, 125, 2625, 2659, 146245, 146334, 21072096, 21072329, 7944268033, 7944268643, 7840993150641, 7840993152238, 20261126305382992, 20261126305387173, 137066519455944225345
Offset: 0
a(0) = 0 + 1 = 1;
a(1) = 1 * 1 = 1;
a(2) = 1 + 2 = 3;
a(3) = 3 * 3 = 9;
a(4) = 9 + 5 = 14.
-
a[0] = 1; a[n_] := a[n] = If[OddQ[n], a[n-1] * Fibonacci[n+1], a[n-1] + Fibonacci[n+1]]; Array[a, 20, 0] (* Amiram Eldar, Mar 28 2020 *)
-
from sympy import fibonacci
f = [fibonacci(n) for n in range(100)]
def a(n):
out = f[0] + f[1]
for i in range(1, n):
if i%2:
out *= f[i+1]
else:
out += f[i+1]
return out
A333591
Alternate multiplying and adding Fibonacci numbers: a(0) = F(0) * F(1), for n >= 0, a(2n+1) = a(2n) + F(2n+2), a(2n+2) = a(2n+1) * F(2n+3).
Original entry on oeis.org
0, 1, 2, 5, 25, 33, 429, 450, 15300, 15355, 1366595, 1366739, 318450187, 318450564, 194254844040, 194254845027, 310224987508119, 310224987510703, 1297050672782249243, 1297050672782256008, 14197516664274574263568, 14197516664274574281279
Offset: 0
a(0) = 0 * 1 = 0;
a(1) = 0 + 1 = 1;
a(2) = 1 * 2 = 2;
a(3) = 2 + 3 = 5;
a(4) = 5 * 5 = 25.
-
a[0] = 0; a[n_] := a[n] = If[EvenQ[n], a[n-1] * Fibonacci[n+1], a[n-1] + Fibonacci[n+1]]; Array[a, 22, 0] (* Amiram Eldar, Mar 28 2020 *)
-
from sympy import fibonacci
f = [fibonacci(n) for n in range(200)]
def a(n):
out = f[0] * f[1]
for i in range(1, n+1):
if i%2:
out += f[i+1]
else:
out *= f[i+1]
return out
Showing 1-8 of 8 results.