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A120490
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1 + Sum[ k^(n-1), {k,1,n}].
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0
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2, 4, 15, 101, 980, 12202, 184821, 3297457, 67731334, 1574304986, 40851766527, 1170684360925, 36720042483592, 1251308658130546, 46034015337733481, 1818399978159990977, 76762718946972480010, 3448810852242967123282
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Prime p divides a(p). Prime p divides a(p-2) for p>3. p^2 divides a(p-2) for prime p=7. p^2 divides a(p^2-2) for prime p except p=3. p^3 divides a(p^2-2) for prime p=7. p^3 divides a(p^3-2) for prime p>3. p^4 divides a(p^3-2) for prime p=7. p^4 divides a(p^4-2) for prime p>3. p^5 divides a(p^3-2) for prime p=7. It appears that p^k divides a(p^k-2) for prime p>3 and 7^(k+1) divides a(7^k-2) for integer k>0.
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FORMULA
| a(n) = 1 + Sum[ k^(n-1), {k,1,n}]. a(n) = 1 + A076015[n].
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MATHEMATICA
| Table[(1+Sum[k^(n-1), {k, 1, n}]), {n, 1, 23}]
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CROSSREFS
| Cf. A076015.
Sequence in context: A020110 A140836 A020134 * A003514 A065598 A100528
Adjacent sequences: A120487 A120488 A120489 * A120491 A120492 A120493
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KEYWORD
| nonn
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AUTHOR
| Alexander Adamchuk (alex(AT)kolmogorov.com), Aug 04 2006
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