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A258138
Smallest m, such that there are exactly n solutions of the equation (m+k)' = m' + k', where 1 <= k <= 2*m and x' = A003415(x), the arithmetic derivative of x.
2
1, 2, 14, 70, 166, 350, 1050, 2002, 1870, 4730, 5170, 9350, 15106, 29050, 45318, 65450, 25850, 139590, 75530, 129250, 180950, 226590, 383350, 341530, 377650, 551650, 697950, 439450, 1127610, 1489950, 1004850, 1654950
OFFSET
1,2
COMMENTS
A099305(a(n)) = n and A099305(m) != n for m < a(n).
LINKS
EXAMPLE
a(3) = 14, 14' = 19:
1: (14 + 7)' = 21' = 10, and 14' + 7' = 9 + 1 = 10,
2: (14 + 11)' = 25' = 10, and 14' + 11' = 9 + 1 = 10,
3: (14 + 28)' = 42' = 41, and 14' + 28' = 9 + 32 = 41;
a(4) = 70: 70' = 59:
1: (70 + 8)' = 78' = 71, and 70' + 8' = 59 + 12 = 71,
2: (70 + 35)' = 105' = 71, and 70' + 35' = 59 + 12 = 71,
3: (70 + 55)' = 125' = 75, and 70' + 55' = 59 + 16 = 75,
4: (70 + 140)' = 210' = 247, and 70' + 140' = 59 + 188 = 247.
PROG
(Haskell)
import Data.List (elemIndex); import Data.Maybe (fromJust)
a258138 = (+ 1) . fromJust . (`elemIndex` a099305_list)
CROSSREFS
Sequence in context: A084770 A086243 A375874 * A206947 A203241 A072888
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, May 21 2015
EXTENSIONS
More terms from Manfred Scheucher, May 23 2015, May 25 2015
STATUS
approved