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A338917
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a(n) = sum_of_digits(a(n-1)^a(n-2)) where a(1)=1 and a(2)=2.
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1
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1, 2, 2, 4, 7, 7, 25, 34, 151, 331, 1690, 3265, 26449, 64528, 574513, 1671208, 16090657, 54199564, 559922497, 2133503863, 23506132363
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OFFSET
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1,2
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LINKS
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FORMULA
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EXAMPLE
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for n=6, a(6) = sum_of_digits(7^7) = sum_of_digits(823543) = 25
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MATHEMATICA
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a[1]:=1; a[2]:=2; a[n_]:=Total[IntegerDigits[a[n-1]^a[n-2]]]; Array[a, 19] (* Stefano Spezia, Nov 15 2020 *)
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PROG
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(SageMath)
a, b=1, 2
L=[a, b]
for n in [1..17]:
c=b^a
c=sum(c.digits())
L.append(c)
a, b=b, c
print(L)
(PARI) a338917(nmax)={my(x=vector(nmax)); x[1]=1; x[2]=2; for(k=3, nmax, x[k]=sumdigits(x[k-1]^x[k-2])); x};
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CROSSREFS
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KEYWORD
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nonn,base,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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