A053064
Alternately append n to end or beginning of previous term.
Original entry on oeis.org
1, 12, 312, 3124, 53124, 531246, 7531246, 75312468, 975312468, 97531246810, 1197531246810, 119753124681012, 13119753124681012, 1311975312468101214, 151311975312468101214, 15131197531246810121416, 1715131197531246810121416, 171513119753124681012141618
Offset: 1
- Felice Russo, A set of new Smarandache functions, sequences and conjectures in number theory, American Research Press 2000
A281254
Concatenate the decimal numbers n n-2 n-4 ...5 3 1 2 4 ... n-5 n-3 n-1 if n is odd, or n n-2 n-4 ... 6 4 2 1 3 5 ... n-5 n-3 n-1 if n is even.
Original entry on oeis.org
1, 21, 312, 4213, 53124, 642135, 7531246, 86421357, 975312468, 10864213579, 1197531246810, 121086421357911, 13119753124681012, 1412108642135791113, 151311975312468101214, 16141210864213579111315, 1715131197531246810121416
Offset: 1
a(13) = 13119753124681012.
-
b:= proc(n) b(n):= `if`(n=1, 1, parse(cat(a(n-1), n))) end:
a:= proc(n) a(n):= `if`(n=1, 1, parse(cat(n, b(n-1)))) end:
seq(a(n), n=1..20); # Alois P. Heinz, Jan 18 2017
-
f[n_] := Fold[ If[ Mod[n +#2, 2] == 0, #2, #1]*10^IntegerLength@ If[ Mod[n +#2, 2] == 0, #1, #2] +If[ Mod[n +#2, 2] == 1, #2, #1] &, 0, Range@ n]; Array[f, 17]
-
def a(n):
if n==1:
return ["1"]
return [str(n)]+a(n-1)[::-1]
def A281254(n):
return "".join(a(n)) # Indranil Ghosh, Jan 23 2017
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