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A289382 a(n) = 2^n mod triangular(n). 1
0, 1, 2, 6, 2, 1, 16, 4, 17, 34, 2, 40, 2, 4, 8, 120, 104, 1, 78, 46, 134, 70, 140, 16, 132, 121, 134, 30, 2, 94, 64, 400, 206, 429, 158, 334, 2, 4, 8, 616, 494, 1, 690, 346, 692, 142, 848, 64, 912, 1024, 8, 796, 797, 379, 1528, 4, 350, 178, 1418, 916, 2, 4, 512, 1056, 32, 2011 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A000079(n) mod A000217(n) = 2^n mod n*(n+1)/2.

a(n) = 1 for n>1 in A272934. - Michel Marcus, Jul 04 2017

EXAMPLE

a(6) = 2**6 mod (6*7/2) = 64 mod 21 = 1.

MAPLE

seq(2^n mod n*(n+1)/2, n=1..100); # Robert Israel, Jul 04 2017

MATHEMATICA

Table[Mod[2^n, n (n + 1)/2], {n, 66}] (* Michael De Vlieger, Jul 04 2017 *)

PowerMod[2, #, (#(#+1))/2]&/@Range[70] (* Harvey P. Dale, Oct 12 2018 *)

PROG

(Python 2)

for n in range(1, 99):  print str(2**n % (n*(n+1)/2))+', ',

(PARI) a(n) = lift(Mod(2, n*(n+1)/2)^n); \\ Michel Marcus, Jul 04 2017

CROSSREFS

Cf. A000079, A000217, A066606, A272934.

Sequence in context: A008905 A136760 A303335 * A062539 A064136 A171898

Adjacent sequences:  A289379 A289380 A289381 * A289383 A289384 A289385

KEYWORD

nonn

AUTHOR

Alex Ratushnyak, Jul 04 2017

STATUS

approved

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Last modified November 22 16:31 EST 2019. Contains 329396 sequences. (Running on oeis4.)